Excel 2007 : Secondary axis alignment

HI EVERYONE!

I need your help. Sorry for my english.

I have XY graph with three lines. The 3rd line is on the 2ndary axis. How can i allign the primary and secondary axis, so they would both have the same y=0. I tried with max, min values, the gap, but nothing. Please help.

P.s. the green line is on 2ndary axis, and it is supposed to cross the x axis where the red is at maximum, because so are the calculations.

Thank you guys for all your replies.
p.