When trying to Link a table from a Progress ODBC connection I was getting something like (reserved error -7748).  In order to fix this I had to create a registry entry under the HKLM.  To do this, open regedit, Navigate to the following registry key:


Then choose the odbc folder name that you are trying to create a link with, mine is called v7.

Right click on the folder name (or anywhere in the white-space on the left hand side).

Select “NEW” >> “String Value”

Name this Value as follows “WorkArounds2”

Double-click “WorkArounds2” and enter the value of “40960” in value data field, then say OK. Here’s a pic of what my registry entry looked like.

That should be it.  You don’t need to restart Access,  just recreate the link, or the import in access. Here’s the explanation I copied from here where they also have other explanations of workarounds for Progress.

“The ODBC Driver Manager incorrectly translates
lengths of empty strings when a Unicode-enabled application uses a
non-Unicode driver. This workaround causes the DataDirect Connect64 for
ODBC drivers to internally adjust the length of empty strings. Use this
workaround only if your application is Unicode enabled.”