whmcs plugin order complete but not working

i have facing problem . my actual whmcs order process complete working but in the wordpress i have using whmcs integration plugin its not works i have mention both url for testing

actual whmcs url :http://www.mysamplewebsite.net/whmcs/cart.php?gid=2

wordpress url :
http://whmcs.oursamplewebsite.com/whmcsportal/cart.php/?gid=2

please guide me ..