UPDATE Query works in odbc/Mysql, but fails in odbc/MS Access

Hello, I have one MS Access DB on the server, and an exact (theoretically) copy of it in MySQL on my machine, so I can test PHP pages on Linux and install them on an NT server (using odbc of course). I can insert and select just fine, thankl to all your help. The problem is that this UPDATE query: UPDATE rec SET Aut = 1 WHERE Un = 20000927230327; works perfectly on PHP/ODBC/MySQL on Linux, while on PHP/ODBC/ACCESS/ it gives this error: Warning: SQL error: [Microsoft][ODBC Microsoft Access Driver] Data type mismatch in criteria expression., SQL state 22005 in SQLExecDirect in C:\domini\m.net\update_db.php on line 54 No cursor Initially I though well, maybe I'm trying to write a string into a number, or something like that, but I can SELECT from that same table using the same format, so what is the trick? Different UPDATE syntax between MySQL and ACCESS? If so, where is an online ACCESS syntax reference? TIA, mweb