cant change apn !

[greenmomma1]

I recently switched to straight talk, I have an unlocked nokia 900. I went to change my apn settings through the network setup app. it wasn't working! so I stupidy reset my phone.. and now the network setup app is gone and its saying my phone cannot install the app! Now I have no idea how to change my apn settings. I tried going into cingular and turning my date roam on and applying the apn setting there to att.mvno but its still not working.. please help!!

 

[pankaj981]

What error are you getting while installing the Network Setup app?