#6. "RE: Meike MK-D7000 battery grip for D7000" In response to In response to 5 Sat 31-Mar-12 05:40 PM by DeanAZ
Menu option d14 is where you set the order for the battery usage. I have mine set to the grip battery first then the camera battery. This works for me but then I have the genuine grip. It's possible that if you have the settings correct there may be a compatibility issue with the 3rd party grip.
If it is a compatibility issue you could dive into the d13 setting and tell it to use the camera battery first when the grip battery is getting low as a workaround. It's kind of hard to do quick tests on how the features work as the batteries last so darned long!