How to implement condition in if-else block in simulink if the condition driving the block is a calculated state from if or else action subsystem blocks?

I am trying to implement a conditional execution of system of ODEs in Simulink. The condition is evaluated using one of the computed states. I wish to use the value of this state as a conditional parameter in the If decision block. However, I am getting an error of invalid loop. Below is a snapshot:

zeta is a computed state (involved in system of ODEs) inside the if action subsystem. I want to use the value of zeta at each time step in the If block to determine whether to use the if action or else action.

I would appreciate any help on this or an alternate method of implementation. Thanks