CT Clamps not reading anything

[smartroad]

Hi! I brought the kit from Mouser which has the SCT016-A16 CT clamps. I have plugged into the board and had to add my own 9V transformer as the kit was for 120 and I am on 240v. The voltage reads mostly right (just needs calibration) but I am getting nothing from the current reading when I try to monitor a 450W oil filled heater.

-edit- This is the kit: https://www.mouser.co.uk/ProductDetail/392-CSCIRCUITSETUP02

Am I missing something? As I read it I just need to clamp around the power lead and plug into the 3.5mm jack, power-up and it should read the current being consumed?

[CircuitSetup]

I'm sorry, I overlooked your question initially.

Are the clamps around the hot wire only? If they are around the hot and neutral the readings will not be correct.