VB interface with Assembly

I tried to pass the value of an array from a VB net program to an Assembly routine.
The value did successfully land on the Assembly by using an x86 platform .
Repeating with the same coding on an x64 platform, I got a corrupted value entering the Assembly routine.
Needless to say, I turned all coding with x64 changed into 64-bit words and registers.
Note that this problem occurs only with arrays, all single variables passed uncorrupted , even on x64.
I tried many different ways but I couldn't find out why.
Could anyone help me, I had first hard time to discover this bug, it lasted a couple of months (not full time, of course).
If needed I can send an attachment.
Even if someone will try the same, it would help to know the result (corrupted or uncorrupted), so that I may focus on the "guilty one", VB net or Assembly ?)
Thanks anyone helping !!
Gian