"She orders him to write."
Translation:Zij beveelt hem om te schrijven.
Actually, in formal, written Dutch it's better to leave out 'om'. Then you should only use 'om' when it's used to indicate a goal, for example: ik gebruik een pen om te schrijven/Ik doe dit om je te helpen... In those 'goal' cases it's always mandatory to write 'om', also in informal Dutch.
I think 'bestellen' means to place an order where as bevellen (?) has the other meaning of order which is giving instrictions that one must follow so the meaning would change and the sentance wouldnt make sense. She is not ordering him in that way in this sentance (unless he is for sale?)