If you write Microsoft Access databases with basic VBA code and no fancy Windows calls, you will find your database will run with Office 32 bit and Office 64 bit with no problems. But if you have used fancy windows library calls, you are likely to get this bug
The code in this project must be updated for use on 64-bit Visual Basic VBA7. Please review and update Declare statements and then mark them with the PrtSafe attribute.
This issue is discussed in detail here at Microsoft and Conditional Compilation is discussed here
Better still, here is an article by Garry that explains conditional compile in more detail