compile error after porting library for stepper.h | Arduino Compatible Compiler for LabVIEW Discussions | Forum

Hi,
I tried to port the stepper.h library which ships with the Arduino IDE. Mostly to try out a simple example (also because I didn't find an existing example).
Followed the manual and hunted down a few early mistakes like wrong representations in the API VIs.

Now, when I'm compiling a test VI which only contains the "Stepper4Wires.vi" API-VI (which is a rather complicated one in that library) it compiles OK.
But if I add a "setSpeed.vi" API-VI to the test VI then I recieve the following error message:
temp:20: error: 'Node1239Out' was not declared in this scope
setSpeed(Node1239Out);
but the Parameter of setSpeed is not an OutParameter and I didn't declare it as one.

Is there anything obvious I can look after?