Why the right(); command returns both sides of an expression? (SOLVED!)

[Spybot]

Hi DrD!

Is this what you mean?

#cas
test():=
BEGIN
LOCAL M,BY,S,y,x;
INPUT(M,"TITLE","LABEL:");
BY:=CAS.y=M*CAS.x;
S:=CAS.right(BY);
MSGBOX(S);
return 0;
END;
#end

Well it doesn't even execute. I went to CAS view and created this piece of code and I also checked the CAS option.
Why there's no much help about this command?