Question: Plotting gravitational potential field in maple

Hi,

I m trying to plot the gravitational potentialfield of two masses in maple. Im doing my work with inspirtion from this paper:

http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-07-dynamics-fall-2009/lecture-notes/MIT16_07F09_Lec18.pdf

Page 4 and 5. Im able to plot the first graph on page 5, the contour plot of the gravitational potential in graph, by setting y=0. But when i try and plot the function of 2 variables in maple i get nothing that look like what im supposed to get... I have attached a picture of the graph and function in maple.

Using command: contourplot, dosent help much either. Im sorry if the problem is obvious, im really new to maple.

EDIT: attaching doesent work, heres a link: http://img825.imageshack.us/img825/70/12345mq.png

Regards