Problems With The SRM400 Module

after i cross referencing with the user manual of SRM400, it seems that the device is working fine as i got the same readings of waveform as in the user manual. The problem now lies with the VR1 and VR2,which are not functioning as what it said on the manual as they(VR1&VR2) supposed to give different reading of waveform which will then help me to get the measurement i want for it to buzz at a specific distance.

how should i do about it?

thank you