Description
A. ADS has a pretty good desctiption (See Cause A)
B. fnacs(sn$,0,mat x$,cmdkey)
Common causes
A. Attempted to pass a literal to a user-defined function when the function was expecting a variable.
B. CMDKEY is a controled word and can't have a value set or returned in it
Common solutions
A. Pass a variable or remove the ampersand (&) from the function definition.
B. Use CK or CKey - something that's not a BR contoled word
Notes
B. by Charlie and John