“Compact Now” does not work

I have a large pst file about 600MB that I would like to compact but when I hit the compact button I get a dialog box that says compacting but flashes up for one second and disappears. It doesn’t compact my file as if it doesn’t need to be compacted. I tried to compact another file thinking it might be my file that may be corrupt but it did the same thing. Is there anything else I can try?