[Observium] Interface Traffic trend

Is there a config option or change I need to make to get the interface traffic trend option to work? I'm running the latest CE version. RRDtool 1.38 and 1.47 versions. I've only have this running a month, but thought there would be enough data to see a trend.

Also, where would I load MIBs and configure OIDs for Brocade VDX gear?

Thanks in advance, Ken