PB12.6 64-bit issue: GlobalMemoryStatus

I am deploying my PB12.6 app as 64-bit.

Calls to GlobalMemoryStatus are returning low memory.

This is not correct as the memory exists and the 32-bit deployment works.

What can I do to rectify? I read somewhare that I should use GlobalMemoryStatusEx instead.

I tried that but my 32-bit deployment reported low memory!

My app is using the pfc libraries.

Is there a need to convert many function calls to run 64-bit?

Thanks in advance.

Larry