Installing a GFCI Breaker
There should be no problem with this, as long as you've installed the breaker properly.


Read and understand all of the included manufacturers documentation.
Connect the grounded (neutral) pigtail from the breaker to the neutral/ground bar in the panel.
Connect the grounded (neutral) circuit conductor to the neutral (silver) terminal on the GFCI breaker.
Connect the ungrounded (hot) circuit conductors to the hot (brass) terminals on the GFCI breaker (one conductor per terminal).


If the breaker will not set, there are a few things that can be wrong.


The breaker is faulty.
There's a ground-fault in the circuit.
There's a short-circuit in the circuit.
The circuit is overloaded.