anybody help me why this error comes?
Ld /Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Intermediates/APPINESS_V02.build/Debug-iphoneos/APPINESS_V02.build/Objects-normal/armv6/Appiness normal armv6
    cd /Users/imac/Desktop/PROJECTS/TRANING/APPINESS
    setenv IPHONEOS_DEPLOYMENT_TARGET 3.2
    setenv PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/llvm-gcc-4.2 -arch armv6 -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk -L/Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Products/Debug-iphoneos -F/Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Products/Debug-iphoneos -F/Users/imac/Desktop/PROJECTS/TRANING/APPINESS -filelist /Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Intermediates/APPINESS_V02.build/Debug-iphoneos/APPINESS_V02.build/Objects-normal/armv6/Appiness.LinkFileList -dead_strip -miphoneos-version-min=3.2 -framework QuartzCore -lz.1.2.3 -framework SystemConfiguration -framework MobileCoreServices -framework CFNetwork -lxml2 -framework MapKit -framework CoreLocation -framework UIKit -framework Foundation -framework CoreGraphics -o /Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Intermediates/APPINESS_V02.build/Debug-iphoneos/APPINESS_V02.build/Objects-normal/armv6/Appiness

Undefined symbols for architecture armv6:
  "_OBJC_CLASS_$_FBLoginButton", referenced from:
      objc-class-ref in FaceBookController.o
  "_OBJC_CLASS_$_FBSession", referenced from:
      objc-class-ref in FaceBookController.o
ld: symbol(s) not found for architecture armv6
collect2: ld returned 1 exit status

anybody help me why this error comes?
===

Ld /Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Intermediates/APPINESS_V02.build/Debug-iphoneos/APPINESS_V02.build/Objects-normal/armv6/Appiness normal armv6
    cd /Users/imac/Desktop/PROJECTS/TRANING/APPINESS
    setenv IPHONEOS_DEPLOYMENT_TARGET 3.2
    setenv PATH "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/llvm-gcc-4.2 -arch armv6 -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.3.sdk -L/Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Products/Debug-iphoneos -F/Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Products/Debug-iphoneos -F/Users/imac/Desktop/PROJECTS/TRANING/APPINESS -filelist /Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Intermediates/APPINESS_V02.build/Debug-iphoneos/APPINESS_V02.build/Objects-normal/armv6/Appiness.LinkFileList -dead_strip -miphoneos-version-min=3.2 -framework QuartzCore -lz.1.2.3 -framework SystemConfiguration -framework MobileCoreServices -framework CFNetwork -lxml2 -framework MapKit -framework CoreLocation -framework UIKit -framework Foundation -framework CoreGraphics -o /Users/imac/Library/Developer/Xcode/DerivedData/APPINESS_V02-bqlwftkfsewwgtbygfagdyccihhh/Build/Intermediates/APPINESS_V02.build/Debug-iphoneos/APPINESS_V02.build/Objects-normal/armv6/Appiness

Undefined symbols for architecture armv6:
  "_OBJC_CLASS_$_FBLoginButton", referenced from:
      objc-class-ref in FaceBookController.o
  "_OBJC_CLASS_$_FBSession", referenced from:
      objc-class-ref in FaceBookController.o
ld: symbol(s) not found for architecture armv6
collect2: ld returned 1 exit status
