Instructions:
The errorcode 0x0801 occures at two different events.

• An invoked procedure program does not exist, that means, an invoked program number is not available.
• A procedure program will be invoked as a subprogram out of a program, which was already invoked on its part out of another procedure program; so the nesting depth is too big.
  The "subprograms" can not further nested at the moduls FM 353 and FM 354. 
  The following illustration clearifies this behaviour.

Figure 1: Program configuration at nesting of programs

Configuration of a subprogram invokation:    N 50  P1  L2   

N xx      Syntax
P yy       Number of calls
L zz       Program numbers of the subprogram