trivial question: how to add effect to monitor?

Hi,

I use Behringer UB1204 mixer.

I cannot figure out how to get reverb in monitor.

I tried both: connected effect to aux 1 and took signal for monitor from

aux 2 and vice versa. No effect in monitor.

What is the trick? If possible detailed instruction for this mixer.

I use Yamaha stereo effect.



Thanks,

Michael.