What version of the library are you working with? The iOS 3.1c (Compact) version does not require the "-all_load" option.
And to clarify, you're getting errors when you compile your project on 5.1 without our Libraries? I'm not sure if we can be much help in that case. If you meant to say that the project does not compile onto a device with 5.1 with our libraries, then are you deploying for iOS 5.0+? If so, there is a known bug with XCode 5.1 that will misidentify a public API as a private API and will prevent a releasable build. The only solution that bug is target iOS 6.0+, use a prior version of XCode, or wait for Apple to release the next version of XCode.