Callibration Problems - Rekordbox with Vinyl

Hi All

I am having problems succesfull getting rekordbox to calibrate a new Numark ntx1000 turntable. I using the (fantastic!) DJM250mk2. As far as i am aware I've set up everything correctly (phono etc. etc.) and DVS appears to be working 'ok' if a bit choppy. However when trying to calibrate I get what appears to be fairly decent 'circles' but always return an 'Error' message. I have another turntable (Audio technica) which I did have problems calibrating when on 'B' channel, but moving to channel 'A' seems to fix. As I writing this, I need to move to numark to see if it calibrates on Channel A. Could it be the mixes at fault?

Any ideas its driving me mad :)