dragon.var writing variables QtDragon

Hi,  I am trying to read and to write variables in dragon.var.  Purpose is to know the on/of status of a laser and a spindle (on or off).  I can read the values through MDI with a DEBUG message. I can also write through the MDI. So the 2 variables (#5381 & #5382) that I want to read and write are accessible.  However, I cannor achieve to set the values during initialisation of QtDragon. I tried to do this through a subroutine that is called in the INI file (STARTUP_GCODE = o<init_variables> call, but it doesn't work.  Any ideas how to solve this?

I am not sure why STARTUP_GCODE doesn't work - an example subroutine would help me investigate.
Usually for this sort of thing a preference file entry would be used. Any reason that you must use gcode variables?