How do I use ode15s to solve two simultaneous ODE's?

I am trying to solve two second order ODE's and plot the results. The equations describe the acceleration of a spacecraft in the 3-Body Earth-Moon system. I have converted the equations into first order and sent them through the solver, with correct initial conditions, but the result is not what it should be. The result should be a circular orbit just slightly above the Earth, the circle on the right side of the plot, but it is clearly wrong if you run the code. I am thinking the code doesn't know that the third and fourth initial condition are y position and velocity and it thinks y(3),y(4) are x''' and x''''... which they aren't. I don't know how to tell the solver that y(3),y(4) are y and y'.

[Torsten]

The equations that you solve in the attached code are

x''=2*y'+x-((1-mu)*(x-mu)/(((x-mu)^2 + y^2)^(3/2)))-(mu*(x+1-mu)/((((x+1-mu)^2 + y^2))^(3/2)));
y''=-2*x'+y-((1-mu)*y)/(((x-mu)^2 + y^2)^(3/2)) - (mu*y)/((x+1-mu)^2 + y^2)^(3/2)

If they are correct, then something else must be wrong if the results are not as expected.

Best wishes

Torsten.