Coloring a cell using LEN with Conditioning formating , but the number is an interval?

Not logical. Try this:

=AND(LEN(C2)>=28,LEN(C2)<=40)

A couple of things I notice:

1) For some reason, the third =AND(...) rule (the one testing for string length between 28 and 40) had extra quotation marks in it, so that it was really just a text string and not a formula. I edited the rule formula to remove the extraneous quotation marks, and it seemed to work correctly.
2) 0 is both equal to 0 and less than 28. Because conditional formatting evaluates rules in order from top to bottom, when length is 0, it will be formatted green like others that are less than 28. I checked the "stop if true" box next to this rule, so that conditional formatting will stop when length is 0 and not continue to evaluate the other conditions.

Is that closer to what you are expecting it to do?

It is now that I have removed the ".........""" that were surrounding it!

It's working in the attachment. Are we sorted now?

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