@dinesh_kumar_r Being the type who doesn't make assumptions, can you provide the exact rule you used? I'm asking just because everyone approaches problems differently, and this may feel like a super-simple approach. The Regex I would start off using, based on what you stated in your question would be.
I escaped the colons simply out of caution, but I would expect this to work.
The only other thing I would validate is the format of the first field in your classification. If it's text, you should be fine. If you are still having issues, I also agree you should be contacting Customer Care to determine the technical problem. Best of luck!