G2X data logger - Tach signal??

[mmasse]

I recently bought a G2X data logger. I tested it on the track last week and it is great. I am having one problem, though. I am not able to get a TACH signal. I have a 3.6 conversion and Iam taking the tach signal directly from the wire that goes from the DME to the Tachometer. The tachometer in the dash is working, but the G2X data logger is not capturing the signal. Any suggestions?

Thanks