Column Validation only when item has a value

Question

I have a list where I'd like to enforce that for one of my Single Line of Text fields, the user must enter a value with exactly 3 characters. However, the field is not required so I only want the validation error to display when the user has entered text. This is what I have in the column settings under Column Validation

=AND(LEN([My Text Field])=3,(NOT(ISBLANK([My Text Field]))))

And then I have a message in User message: Please ensure text field has 3 characters

Problem I'm having is that the error is still displaying when I try to add new items (specifically using datasheet edit view) where the field is blank. Is there a problem with my formula?

Answer 1

Working forumla:

=IF(AND(NOT(ISBLANK([My Text Field])),NOT(LEN([My Text Field])=3)),FALSE,TRUE)