Which data card you are using?
In the Mobile Partner installation folder (e.g, C:\Program Files\Mobile Partner), there is a XML file called DeviceInfo.xml. Open it with notepad or any editor.
Search for . Inside this tag add ur data card brand (e.g. ) and save it. Now open the Mobile partner and connect to the n/w. Click USSD and give the short text for balance check (e.g, *123#) and send.