This morning I am having real trouble with GIB COVE 45 not sticking to walls. The paster is really smooth but in less than five minutes it starts to go hard and I can't apply the paster to the GIB cove. If I add more water it would become lumpy.

I've tried three times and when I got it up to the wall it would not sick. I am going as fast as I can. Can GIB Cove 45 go bad? It is a few years old.