What is wrong with my code??

*** Variables:
mswhere1 = ''
mswhere2 = ''
director = "'Brady'"

mswhere3 = iif(len(allt(director)) = 0,; mswhere2,iif(allt(len(mswhere2)) = 0, director,;
mswhere2 + ' and ' + director))

*******
I got the error 'Function argument value, type, or count is invalid'

Thanks a lot.