It happens, but that wouldn't be my first assumption. Have you tried doing an exclusion on the switches first? (Not usually necessary if they're new, but it happens.) See:
Also, have you verified that your Z-Wave region is set correctly (I assume US) in Settongs > Z-Wave Details and that you're following the inclusion (and exclusion) process for the device, which for these I think is three taps on the config (small) button?
