OTG Port On Pioneer Not Working

As I did ran out of USB Ports on my Pioneer FreedomBox I wanted to use the the third USB port, it is the OTG USB mini B port on the Lime2 Board. But after trying it on several Pioneers (with latest updates) I noticed, that this ports are not working. So I wrote Olimex and they said, that the port is working with their images. So it must be a driver issue on the FreedomBox. Has anyone a running OTG port? And if so, how did you get it running?

Thanks
David