For al long time is did not manage to use the fibaro dimmer 2 S2 button to toggle the state of an other device.
Scenes did not fire at all, fired twice or even if i pushed the S1 switch.
My setup:
fgd212 scene function activated
S1 connected to a momentary switch to dimm a light bulb connected to the dimmer
S2 connected to a momentary switch to fire scenes via single and double click (toggle the state of two different wall plugs)
Now i found a solution which works perfect for me. Most solutions on this forum make use of sl_SeneActivated I did not fully understand why because this device parameter never seemed to change. I tied a different route see attachment
I hope it helps someone.