On your interface make sure that all channel pads are off and phantom power is on.
Back in Sensory Percussion, look at the input meter on track 1 as you strike the corresponding drum sharply in the center of the head. The input meter should register signal. Repeat this step for every channel you are using in Sensory Percussion.
Sensory Percussion versions 1.3 and up has an auto level feature. Set your interface gain at a reasonable level where loud hits like rimshots do not peak. With auto level on, Sensory Percussion will then dial in the perfect gain amount for your Sensor. However, if there is a problem with your interface, XLR cable, or sensor this feature can sometimes disable audio from the sensor entirely - if that happens you can turn the feature off by clicking on the "auto level” button on the bottom of the threshold panel.
If you cannot get signal into Sensory Percussion without turning off the auto level feature (but phantom power is on and your sensors have powered up), it means that something might be wrong with your XLR cable, interface, or sensor.
If you have done all of the above and there is no signal registering in Sensory Percussion, check out No audio coming into Sensory Percussion. If you are running macOS 10.14 (Mojave), you may just need to grant audio input access to Sensory Percussion: Check the following setting to make sure Sensory Percussion has access: System Preferences > Security and Privacy > Privacy > Microphone > Allow Sensory Percussion access.