Trigger variable listed values

[#1]

Ï have variables with listed values.

No i want to change them with a trigger.

How can i do this?

The normal way doesn't work for for this type of variables.

For example i have a variable named: vPgChoice

His listed Constant the code is:

=concat({<Collectie={'$(vCollectieKeuze)'},Eigenaar={'B&C'},CollectieGroep=>}PrijsGroep,';',LoadOrder)

After change the Productgroup, i want to pick up the first ProductgroupCode.

When i use the external trigger

Variable =vPgChoice

Value = Subfield( Concat .....,';'1) or for test PG-1

On change or select the productGroup Field, he does nothing.

Regards Dirk