runScript expression with Indirect tag

Hi , i’m trying to use the run script function with an argument that as a custom properties. it’s not working i’m missing something but don’t know what.

here is the script
runScript(“shared.backgroundcolor.backgroundcolor”, 0, tag("[Master_par_Tags]Batching/A220/AGT SPT/AGT"+{Root Container.monIndex}+“PLC/SPT_1”))

I try also like this
runScript(“shared.backgroundcolor.backgroundcolor”, 0, (tag("[Master_par_Tags]Batching/A220/AGT SPT/AGT"+{Root Container.monIndex}+“PLC/SPT_1”)))

Please note that {Root Container.monIndex} is binded with the value of a slider.

Thanks