Regexpismatch() not working

Hi, I am new to Seo tools and Rep-Exp in Excel. I installed latest version of Seo Tools and checking with RegExpIsMatch function.

I am trying to check the below strings:
AB1C
1B2A

To check I am using '=RegexpIsMatch(A3,"[A-Z0-9]{4}")' but it is not showing True or False.
Please help me out on this and if I need to enable any settings please let me know.
Thank you.

Perhaps you need to use semi-colons are argument separators? Should work: