Yes, Farinaz, as Anarel notes it doesn't sound like you have a US DX. Incidentally, the first four digits of my US DX are B004. In which case, to go from 2.3 to 2.3.3, try the bin file at:
http://www.amazon.com/update_kindle_dx_gw.bin
If that works, then the next step is the bin file at
http://rapidshare.com/files/38188633..._472900057.bin
Let us know how you get on.