Wrong Drag and Lift Coefficient when changing AoA
 

I'm trying to calculate Drag and Lift Coefficient of NACA 2415 airfoil. When flow with velocity of 10m/s passes over the airfoil with angle of attack (AOA) = 0, the CD and CL is as same as the data giving in Theory of wing sections.
Unfortunately, when I change the AOA, the result is terrible, even the CD is negative.:confused:
I try two model (k-e and SST) with Y+ calculated according to http://www.cfd-online.com/Tools/yplus.php ,but it does not change :(
Please give me some explain and solution for this problem :)
Thanks in advance.
PS: I attack my mesh for convenience http://www.mediafire.com/?498bgm94khh9bf1

recheck your drag calculation components in Monitors. Try to visualize the components according to your coordinate system.