gnus-agent-read-agentview error

[ptk]

Hi Everyone,
I get the following error after starting gnus:

[snip]
Checking new news...
byte-code: gnus-agent-read-agentview no longer supports version 1.  
Stop gnus, manually evaluate 
gnus-agent-convert-to-compressed-agentview, then restart gnus.
Loading encoded-kb...done

I've googled, but to no avail. I'm not an expert and be missing the 
obvious - if so, please advise and point it out.

Thanks in advance,
ptk