object file format invalid or unsuitable Command /usr/bin/codesign failed with exit code 1

i tried running ios 5 on my mac machine along with xcode3.2.4 but after running that(ios 5) if am trying to run my prject in xcode3.2.4 then its thowing this error... object file format invalid or unsuitable Command /usr/bin/codesign failed with exit code 1

开发者_Python百科

got stuck ..any idea why this is happening?