I need a way out of a situation that you may know the solution to it.When I follow from a cold&dark situation the startup of the APU as per the book,
my EGT gauge not revving up. Would you know if it's a PMDG snag or a code 18 error( that would be me at 18" from the PC) ?

Guy Reinhardt

Guy, I recommend the Tutorials.  Tutorial #2 steps your through a preflight at a gate and starting the APU is on pg 60.  My first thought is that you are not clicking the APU switch all the way to start.  It is a three-way OFF/RUN/START switch.

...and it takes a minute if you go straight to the momentary start position for the apu power plant electronics to initialize before the start process begins.