The element isn’t getting hot.
First check that the transformer has power.
Make sure the circuit breaker is on.
Check that the transformer is producing at least 24v
Using your tester go to the first set of connectors on the element and see if the reading is at 24v
Go to the last element on the floor and repeat the test. If there is 24v, that’s good.
If you have 24v at the first element but not at the last there is a wiring problem. A bad connection or something has been severed. All can be easily repaired.
If you have 24v from the beginning for your element to the end but it does feel warm to you, don’t worry.
The reason may be because of one of the following reasons:
You may be installing this in the summer or on a hot day. The element “self regulates” and if the room you are in is hot it won’t come on. If you have 24v from the beginning to the end you have installed it properly and it will heat your floor when it gets cold.
If you are in a cold room, and you have 24v throughout it may not feel warm because the heating element needs something on top of it to heat. Without some material on top to heat the heat being generated dissipates too quickly and never gets to its 83 degree preset temperature. If you want put cardboard on top and leave it for 15 min so it can build some heat. Then using a temperature gun test it. If you are installing the element directly on top on concrete without insulation the element will try to heat the concrete first before any heat will rise to the surface. Because warm moves to cold. This may take days before the heat can have satisfying effect.
Remember, if you have 24v from the beginning of the element to the end, you have done it right. Don’t forget for best practice install using the fail-safe method.