don't know what the problem is, but I can debug things in DBI by using the 'trace' method.

...some perl code here
DBI->trace(1,"/path/to/logfile");
... DBI code that gives errors here ...
DBI->trace(0);
...some perl code here
[download]

This will show you what SQL actually gets executed. Comparing that to a (working) query you do directly into MS Access might give you hints on what's wrong here.