Error building

Hi,

When I try to build Cocos2d-x in QtCreator I receive this error:

C:-ndk-r9/toolchains/arm-linux-androideabi-4.8/prebuilt/windows/bin/arm-linux-androideabi-ar: unable to rename ‘libchipmunk.a’; reason: Permission denied

I’m using windows 7 64 bits, cocos2d-x3.0alpha0, Qt 5.2.0, QtCreator 2.8.82

I have full access control on c:
Any idea?