Stale Pointers

What can make a CUBLAS pointer go stale? My goal is to add rows to a matrix as my application produces them, and then do some matrix algebra on what I have so far. Allocation goes fine, but the pointers are stale (or dead) by the time I try to use them. Even trying to write just a single element fails. The pointers are definitely unchanged from the values assigned by cublasAlloc(), and work just fine if I try to use them immediately. Copying from a constant array ([1,2,3,etc]) fails even when using code that worked fine immediately after allocation.

Is there a cleanup of some sort that I need to prevent?