If you select a language code in the Data Source Settings for a language which has no exported language module, you will receive the following error upon selecting the "Test Connection..." button:
Complete text of error message is:
The Dynamics NAV Language Module could not be loaded, table and field captions may not be recognized. It is highly recommended that you export your language module from Dynamics NAV.
To resolve this issue, you can do one of 3 things:
1. Modify your Jet Data Source Settings by choosing a language code for which there is already an exported language module.
2. Modify your Jet Data Source settings by choosing "000 - Do not load language module."