You may want to list what "the device" and the operating system is. What version of ArcPad?
I don't use MDB specifically, so have no answer for you based on the info you have provided. But to get you going, here are a couple other threads re: ArcPad, and MDBs (with ArcGIS10) which might put you in the right direction:
mdb layer format on ArcPad
how to open a*.mdb file in ArcGIS 10?
I do remember that on a windows I had issues on the mobile devices because I did not install the Microsoft SQL Compact Edition before installing ArcPad. Paraphrasing what tech support told me about this
...when launching ArcPad on their desktop PC, when ArcPad 10.0 gets installed, it will install the Microsoft SQL Server Compact Edition v3.1 in the Program Files directory. The Microsoft SQL Server Compact Edition format is what the AXF file format is based on. Therefore because ArcPad 10.2.1 did not install that on the machine, that error was being produced. <<my error was talking about the Compact Edition specifically>> ArcPad will run successfully but will not be able to open AXF files. Throughout our troubleshooting, we ended up uninstalling 10.2.1 for ArcPad and reinstalling 10.0.4 and that had installed the Microsoft SQL Server Compact Edition v3.1, which resolved that error. We then removed 10.0.4 and reinstalled 10.2.1.
