i cant zoom out in scene

every time i try to zoom out on this game im making it wont let me so i tested my scroller on my mouse and its fine i did every thing that could possibly be wrong help me please!!!!!!!!!!!!!!!!!!!!! i realy want to finish my game but i cant move!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

select the object then press F key in keyboard.. it ll work