App Store---> an error has occurred

hello all
i recently bought an application from app store but the installation never finished. After that i closed app store application and opened it again and in "purchased" tab there is a "an error has occurred" message and next to that it says the application is installed but it is not.
Can someone help?

I have tried to reset the app store application throught debug menu but it didn't work.

i use:

OS X mountain lion 10.8.2

maybe it had something to do with my internet cause i used mobile internet to connect. I just used Wi-Fi a while ago and the installation completed just fine.