Help needed with Arguments of a Synthdef

Dear Community,
can anybody give me a short introduction to arguments of a Synthdef.
I need not help to write the Synthdef at self.
My Problem is that I would create a Synth with a special argument.
This Argument should control a certain aspect of this synth.
I have try different names for this Argument.
And I have full acceptance of this Argument by the .set(“Argument-Name”, 12); Command.
But It will not be accepted by a routine with a Syntdef Call.
I think maybe it should have another name, in respect to the special arguments in Supercollider.
Or is there to much arguments ???

Thanks in advance

hi CreCo – could you share a minimal example of the code that you’re running?

Oh, sorry
It is my stupidity I have sleep a night … working up early … see a missing “,” … and the Program run.

A very sorry