I'm trying to check if the 4th letter in a string is not s or S using the following regular expression.

`Regex rx = new Regex(@"A[2-6][025][^sS].*");`

In Addition I want corresponding three letter strings to match (e.g. "A30").
Unfortunately the Match check returns false.
Does someone know what I'm doing wrong and how I can alter my regex?

`rx.Match(test).Success`