iRule - select rate class based on source IP match in data group

Thank you for your response. I found the issue was in the definition of the data group, the format was off a little bit in that I added characters that I didn't need to include manually. For example the first entry now looks like this -

network 10.50.0.0/22 { "rateclass1" }

I did try using your iRule except I kept when CLIENT_ACCEPTED rather than using when HTTP_REQUEST. The iRule you provided does work.

Thanks again for your help!