Known issue. This is more or less abandonware.
Read my previous post, which is right before your post for details and workarounds.

Quote Originally Posted by coldfire0078 View Post
i'm use zencart 1.5.1 and installed Reward Points Full Suite v2.5.
When i test to pay with paypal standard (it's go paypal site and return). I can see the reward point in checkout page but after payment, no points pending or earned.
but if i test to pay with Western Union (it's not go the third part site). all works well, i can see points pending, then earned after delivery.
need kindly help! thanks you very much.