you have to view the page source to see the error:
<b>Fatal error</b>: Call to undefined function mhash() in <b>/home2/charles4/public_html/WA_eCart/checkoutScripts/WA_simlib.php</b> on line <b>30</b><br />
sounds like your php server does not have the mhash library enabled.
try changing the WA_eCart/checkoutScripts/WA_simlib.php file to use the hash function instead.
change:
return (bin2hex (mhash(MHASH_MD5, $data, $key)));
to:
return (bin2hex (hash(MHASH_MD5, $data, $key)));