737 engine startup problem

[erwdes]

I love the 737 model, but I'm having a small issue with starting the plane up. I start the engines with the engine start switches, but when I activate the engine fuel control switches, N1 immediately goes to the maximum instead of slowly making more revolutions. Throttles are on idle. Is this a bug in the airplane model or am I doing something wrong here? Can someone help me out? Thanks!