SQL & PL/SQL

I'm having some issues using two nested loop both using a db_link to a MySQL database;
if I just select some records from the first loop and then other records from the second nested one and simply commit.. (or inside the second loop or outside the second loop, so inside the first loop)... it raise an exception error: 01002 fetch out of sequence.

It seems when I commit it brokens the "pipe" created using the db_link to MySql database;
indeed if I use the same code quering table in the user schema, it naturally works.
It fails also using only one loop and the db_link to MySql...

I Just would like to know if someone else has experienced this kind of problem using db_link (to non Oracle databases), commit and loop ...

Thanks.