How to callup a new created function block faceplate

I need to callup a function block faceplate for an AO function block. This functionality is not available (as for an AO faceplate).

Now I can create my own faceplate (I did) and my own function block faceplate (did not finish yet, but a start exists to be tested).

Now I need to call the newly created function block faceplate, which is done by calling 'frszLoad_iafb'. This function has 3 parameters:

strPic as string, strNMB as string and lngDoMonitor as Long.

For strPic only the CurrentValue of a gs-variable from frsVariables is accepted. No string "PDG_AO_fb_fp" nor User.gs_iafb_ao.CurrentValue (which is PDG_AO_fb_fp) is accepted. In the last two cases, the message "the function block faceplate PDG_AO_fb_fp could not be found". Also when another fb-faceplate (eg. pid_fb) is called, the message is the same. showing the requested filename, but no faceplate.

How can I callup a new created function block faceplate?

(DeltaV 10.3.1)