Syntax issue with a Discount

//eCart Rule

function WAEC_eCart1_promo()  {

  $totalDiscount = 0;

  if (true && ((sizeof($this->Items) > 0) && (( $_POST["promocode"] <>'' )))) {

    $totalDiscount += ($this->TotalColumn("TotalPrice") * ($row_promo['prDiscount']));//Result

  }

  return WA_eCart_FormatNumber($totalDiscount, $this->ForceDecimalsC, $this->DecimalPlacesC);

}

//eCart Rule

I believe that my syntax for this: ($row_promo['prDiscount'])) is incorrect because the discount does not set. If I replace this with a simple value it works fine.

This snippet is from the included eCart page.
The value is setting. I can display it on the Confirmation page but I cannot seem to use it in my discount code.

Have I expressed it incorrectly?

you should not use recordset values in your discount rules, instead, save he recordset value to a session using the Set Session Value behavior, and use the variable in your discount rule.

I wondered about that, but I have done it this way before in ASP so I figured it should work.

Thanks for the suggestion.

recordset data is not persistant, sessions are. the recordset may get set on one page, but not on another that would cause the the discount to fail if you went to a page where the recordset does not exist.

rather than define the recordset on all pages of your site, use sessions to save the recordset value so that it will persist through the other pages once set.