having problem with selectremove and if statement...

Hi, im having trouble with selectremove. Im trying to select R(z)>=0 or if R(z)=0 then Im(z)>0, i tried this:

selectremove ( if z--> R(z)>=0 else R(z)=0 then Im(z)>0 end if , % );

but its not working, any help would be much appreciated.

Thanks.