Validation rule is not doing what I want

[Charlie]

I have set a validation rule on a field of data to allow only data in the following format to be entered, EG: ABC123
I used this method Like"[ABC]###" but the **** thing will not allow me to enter ABC123 or anything else in this format into the field, it also tells me my data which is already there is invalid.
this is driving me insane, I did not think there was a wrong way to do this but I must have somehow.

Could someone please put me out of my misery.

Charlie

 

[Mr Ed]

Use an input mask
ie enter aaa000 as an input mask

 

[Charlie]

Done it

I solved it mate, i used Like "[A-Z][A-Z][A-Z]###"

Thanks for the post anyway.
Charlie