same problem
I have a same problem, checkout redirect just reload kart.php page back. 
and here is the source.... place please help me!!!
Juha 
<?php if(!session_id()) session_start(); ?>
<?php
//WA eCart Include
require_once("WA_eCart/eCart1_PHP.php");
?>
<?php
$eCart1->GetContent();
?>
<?php
// WA eCart Update
if (isset($_POST["eCart1_Update_100"]) || isset($_POST["eCart1_Update_100_x"]))     {
  $eCart1->UpdateCart();
  $Redirect_redirStr="index.php";
  if ($Redirect_redirStr != "")     {
    $eCart1->redirStr = $Redirect_redirStr;
  }
  $eCart1->cartAction = "Update";
}
?>
<?php
//WA eCart Check Out Update
if (isset($_POST["eCart1_Checkout_1"]) || isset($_POST["eCart1_Checkout_1_x"]))     {
  $eCart1->UpdateCart();
  $eCart1->cartAction = "CheckOutUpdate";
}
?>
<?php
// WA eCart Continue Shopping
if (isset($_POST["eCart1_Continue_100"]) || isset($_POST["eCart1_Continue_100_x"]))     {
  $Redirect_redirStr="";
  if (true && isset($_SESSION['WAEC_ContinueRedirect'])) {
    $Redirect_redirStr=siteToPageRel($_SESSION['WAEC_ContinueRedirect']);
  }
  if ($Redirect_redirStr != "")     {
    $eCart1->redirStr = $Redirect_redirStr;
  }
  $eCart1->cartAction = "Continue";
}
?>
<?php
// WA eCart Clear Cart
if (isset($_POST["eCart1_Clear_100"]) || isset($_POST["eCart1_Clear_100_x"]))     {
  $eCart1->ClearCart();
  $Redirect_redirStr="";
  if ($Redirect_redirStr != "")     {
    $eCart1->redirStr = $Redirect_redirStr;
  }
  $eCart1->cartAction = "ClearCart";
}
?>
<?php
//WA eCart Redirect Check Out
if (isset($_POST["eCart1_Checkout_1"]) || isset($_POST["eCart1_Checkout_1_x"]))     {
  $Redirect_redirStr="";
  if ($Redirect_redirStr != "")     {
    if (isset($_SERVER['QUERY_STRING']) && $_SERVER['QUERY_STRING'] != "")     {
      if (strpos($Redirect_redirStr, "?") === false)     {
        $Redirect_redirStr .= "?".$_SERVER['QUERY_STRING'];
      }
      else     {
        $Redirect_redirStr .= "&".$_SERVER['QUERY_STRING'];
      }
    }
    $eCart1->redirStr = $Redirect_redirStr;
  }
  $eCart1->cartAction = "Checkout";
}
?>
<?php
// WA eCart Redirect
if ($eCart1->redirStr != "")     {
  session_commit();
  header("Location: ".$eCart1->redirStr);
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Untitled Document</title>
<link href="WA_eCart/CSS/eC_Clean_Pacifica_Verdana.css" rel="stylesheet" type="text/css" />
</head>
<body>
<div class="eC_Clean_Pacifica_Verdana">
  <?php
//WA eCart Show If Start
if (!$eCart1->IsEmpty())     {
?>
  <form action="<?php echo ($_SERVER["PHP_SELF"].(isset($_SERVER["QUERY_STRING"])?"?".htmlentities($_SERVER["QUERY_STRING"]):""));?>" method="post" >
    <h2>Your Shopping Cart</h2>
    <table class="eC_ShoppingCart" border="0" cellspacing="0" cellpadding="0">
      <tr>
        <th>Name</th>
        <th  class="eC_PriceItem" >Price</th>
        <th  class="eC_FormItem" >Quantity</th>
        <th  class="eC_FormItem" >Remove</th>
        <th  class="eC_PriceItem" >Total</th>
      </tr>
      <?php
while (!$eCart1->EOF())      {
?>
      <tr>
        <td><img src="" alt="" width="110" height="110" class="eC_ProductThumb" />
          <p class="eC_ItemLabel"><?php echo $eCart1->DisplayInfo("Name"); ?></p>
          <p class="eC_ItemDescription"><?php echo $eCart1->DisplayInfo("Description"); ?></p></td>
        <td  class="eC_PriceItem" ><?php echo WA_eCart_DisplayMoney($eCart1, $eCart1->DisplayInfo("Price")); ?></td>
        <td  class="eC_FormItem" ><input type="text" name="eCart1_Quantity_<?php echo $eCart1->DisplayIndex; ?>" size="3" value="<?php echo $eCart1->DisplayInfo("Quantity"); ?>" /></td>
        <td  class="eC_FormItem" ><input type="checkbox" value="<?php echo $eCart1->DisplayInfo("ID"); ?>" name="eCart1_Delete_<?php echo $eCart1->DisplayIndex; ?>" /></td>
        <td  class="eC_PriceItem" ><?php echo WA_eCart_DisplayMoney($eCart1, $eCart1->DisplayInfo("TotalPrice")); ?></td>
      </tr>
      <?php
  $eCart1->MoveNext();
}
$eCart1->MoveFirst();
?>
    </table>
    <div class="eC_OrderSummary">
      <table border="0" cellpadding="0" cellspacing="0" class="eC_CartSummary">
        <?php
//WA eCart Merchandizing Show Start
//ecart="eCart1"
if ($eCart1->GetDiscounts() > 0 || $eCart1->GetCharges() > 0 || $eCart1->GetShipping() > 0 || $eCart1->GetTax() > 0)     {
?>
        <tr>
          <td class="eC_Subtotal eC_SummaryLabel">Sub-total</td>
          <td class="eC_Subtotal"><?php echo WA_eCart_DisplayMoney($eCart1, $eCart1->TotalColumn("TotalPrice")); ?></td>
        </tr>
        <?php
//WA eCart Merchandizing Show End
//ecart="eCart1"
}
?>
        <?php
//WA eCart Merchandizing Show Start
//ecart="eCart1"
if ($eCart1->GetDiscounts() > 0)     {
?>
        <?php
//WA eCart Merchandizing Show End
//ecart="eCart1"
}
?>
        <?php
//WA eCart Merchandizing Show Start
//ecart="eCart1"
if ($eCart1->GetCharges() > 0)     {
?>
        <?php
//WA eCart Merchandizing Show End
//ecart="eCart1"
}
?>
        <?php
//WA eCart Merchandizing Show Start
//ecart="eCart1"
if ($eCart1->GetShipping() > 0)     {
?>
        <tr>
          <td class="eC_SummaryLabel">Shipping</td>
          <td><?php echo WA_eCart_DisplayMoney($eCart1, $eCart1->GetShipping()); ?></td>
        </tr>
        <?php
//WA eCart Merchandizing Show End
//ecart="eCart1"
}
?>
        <?php
//WA eCart Merchandizing Show Start
//ecart="eCart1"
if ($eCart1->GetTax() > 0)     {
?>
        <tr>
          <td class="eC_SummaryLabel">Tax</td>
          <td><?php echo WA_eCart_DisplayMoney($eCart1, $eCart1->GetTax()); ?></td>
        </tr>
        <?php
//WA eCart Merchandizing Show End
//ecart="eCart1"
}
?>
        <tr class="eC_SummaryFooter">
          <td class="eC_SummaryLabel">Total:</td>
          <td><?php echo WA_eCart_DisplayMoney($eCart1, $eCart1->GrandTotal()); ?></td>
        </tr>
      </table>
    </div>
    <table class="eC_ButtonWrapper" cellpadding="0" cellspacing="0">
      <tr>
        <td><input type="submit" name="eCart1_Continue_100" id="eCart1_Continue_100" value="Continue Shopping" />
          <input type="submit" name="eCart1_Clear_100" id="eCart1_Clear_100" value="Clear Cart" />
          <input type="submit" value="Update Cart" name="eCart1_Update_100">
          <input type="submit" value="Checkout" name="eCart1_Checkout_1"></td>
      </tr>
    </table>
  </form>
  <?php
//WA eCart Show If Middle
}
else     {
?><table><tr><td>The cart is empty</td></tr></table>
  
  
  
  
  <?php
//WA eCart Show If End
}
?>
</div>
</body>
</html>

 














