[Observium] mysql app

Hi all, Please give a help here, I´m adding mysql app to a host. I have configured the agent at host and telnet to 36602 is ok. I also enabled unix-agent at modules for that host And I see it at polling:

[mysql] => a0:4033341 a1:4020805 a2:120 a3:120 ...

But I still get no images, just the message "Error drawing graph". What could be missing here?

Thanks, Andrés