Smart Cover Sensor Chip

Hi. I replaced the power/volume ribbon in my iPad2. The new ribbon I received has a black material covering the circuitry on the smart cover sensor of the ribbon, whereas the original one did not have anything covering it (see pics). I gently tried removing this black compound but it didn't feel like an adhesive or rubber, and I'm not quite sure how much force to put into it. The smart cover does not wake or put to sleep the iPad with this replacement and I'm thinking it has to do with that black compound....

Or is this a case of reversed polarity?

Thanks!