Database connection problem on Windows and Ubuntu

Hello,

I'm new to Qt. I've created small application to editing data from database. I was using Qt Creator on Ubuntu. Today i want to open this application on Windows 7, so I installed Qt, compiled it and everything seems to be working. But... on windows my application can't connect to database. Any idea why? I thought if my app works on Ubuntu, it should work on windows too.

Any help will be appreciated :)

Edit:
Ubuntu Qt version : 4.8.1
Win Qt version: 4.7.4

Random guess... you have not built and/or deployed the SQL driver plugin for the database system you are attempting to access, or the corresponding RDBMS libraries are not present. On Windows only the Sqlite plugin is present by default.