Could it be something related to what is mentioned in this article https://how-to.aimms.com/Articles/129/129-MSACCESS-32bit-64bit.html ? 

Thanks a lot, we are using Office 365 32 bits. And AIMMS 4 64 bits. I believe

that might be the problem.

It seems impossible to connect AIMMS 64 bits to Access data (32 bits) through the DSN conector.

How should I modify the DSN?

Thanks a lot

Dear Sonia,

After .mdb on the last line of the dsn file I added an X, so:

.mdbX

In my case it works.

Good luck!

Joost

Thanks a lot but it doesn´t work yet ;(

Are you using Office 2010 ? In my case is Office 365 (32 bits)

I'm using Office 365 but 64 bits. When I used 32 bits before I used a 32 bits version of AIMMS and a 64 bits version. I read in the database using 32 bit, stored the data in a case, closed AIMMS 32 bits, opened AIMMS 64 bit and read in the case. This is of course quite cumbersome.