Did you read (and understand) the "props on the locks"-situation? That's part of the simulation
See the Before Taxi Checklist (pg 46): Propellers..................................................TAKE OFF THE LOCKS
a) Condition Levers...............................................TAKEOFF/LAND
b) Power Levers........................................................REVERSE
c) Power Levers....................................................GROUND IDLE
d) Condition Levers.......................................................TAXI
How to check:
If you have dataref Editor, you can check the dataref sim/cockpit2/engine/actuators/prop_angle_degrees[0]
If you're still on the locks, the angle will keep at around -2.5 if you advance the throttle.
When you go into reverse, once you hit around -14, you are off the locks, and the angle will rise above -2.5 and allow you to take off.