SSRS expression to use IIF and count at the same time

Hi All ;

I need to do the following in the SSRS report

iff (Fields!new_reason4leavingapidname.Value = "Completed,but not achieved main output" or Fields!new_reason4leavingapidname.Value = "Left early, never started" or  Fields!new_reason4leavingapidname.Value = "Left early, not known")

then i need to count applicationformid

Any help much appreciated

Thanks

Pradnya07