64 bit vs. 32 bit problem?

[MarkBinder]

I have a python script that searches a directory and subdirectories to find mxd files and then exports a pdf from the mxd. Here's the problem, when I run it using a 64 bit IDE some maps are missing a layer but when I use a 32 bit IDE the layer show up normally. I'm using ArcGIS 10.2.2 with the 64 bit geoprocessing package installed.

Why would layers show up in 32 bit but not 64 bit?

[JoshuaBixby · Accepted solution]

What is the storage type behind the layers?  64-bit processing has limitations on what types of backend storage types it supports:  Background Geoprocessing (64-bit), see section on Unsupported data types.

[MarkBinder]

Good call. It turns out the data is stored in a personal geodatabase.

Thanks for the help!

[Luke_Pinner]

Additionally, if data is stored in an enterprise GDB, you may need both 32 and 64 bit versions of the database drivers. We have to install a 64 bit Oracle client to access our Enterprise GDB datasets from 64 bit Background Geoprocessing scripts.