Discard stack is closed!

When I am nearing the end of one hand, have a large discard stack, I have a pair, but it wont let me draw from the discards!!! Once it starts not allowing me to draw from discards, I cant draw at all for the remainder of the hand, no matter how many pairs I have that I SHOULD be able to pick up. VERY aggrivating!

pryr4u about Canasta Gold, v2.3