Unable to stop simulation to change a model

Dear,

I am getting the following error:

Cannot change the model when the simulation is running.

the line that causes the error is: delete_line(srcSignal)

I got the value of srcSignal by using get_param(portHandles.Inport, 'Line);

I had to compile the model because I needed to get the port data types. However, When it reaches delete_line(SrcSignal), it gives the error even though I wrote the simulationCommand to stop/pause/the simulation.

Any ideas to solve this?