Synching DJM 900 with Ableton

Hi, I have been having an issue with my DJM 900 and Live. The master clock in Live fluctuates quite erratically. The tracks are in sync for a couple bars before they start to deviate even when the bpm's are aligned. The other issue I have is when I press the quantize button on my mixer. The "grid" light keeps flashing even though everything is quantized. Thanks for your help.