doing pascal at college need some help with this as it is doing my nut in this the program i have a company called brians building firm i have to put to screen a menu with 4 choices 1 min/max sales 2 average sales 3 attendance figers and 0 for quit these sales will appear on screen as a bar or table chart i have the problem were it says operhand types do not match operator here it highlights on the in bit of the code if you could help me i would appreciate it so much give me a shout at my email address cheers.

program get_option;
                       writeln('viewing data');
                       writeln('press T for table of data');
                       writeln('press B for chart of data');
                       if not option in ['T','t','B','b']then
                       writeln('invalid option');
                       untill option in ['T','t','B','b']

the whole program code will be attached.
[Email snipped]

Pass the variable "option" as a parameter to the ReadLn function.