I'm using the "App Measurement for iPhone" libraries to build an iPad application. Previously I was using the iPhone 3.2 SDK and things worked great when building for both the simulator and the device. The other day I upgraded to the 4.0 SDK to try out some new APIs. My existing iPad project still targets the 3.2 SDK, but the simulator builds no longer link due to this error: Undefined symbols: "_OBJC_CLASS_$_OMAppMeasurement", referenced from: objc-class-ref-to-OMAppMeasurement in xyz.o ld: symbol(s) not found collect2: ld returned 1 exit status The device builds still link and run fine. Since I'm still targeting the 3.2 SDK, I'm guessing this is more of an Xcode / gcc / etc. problem than an iPhone SDK problem, but that really is just a guess. I used 'nm' on both versions of the Omniture libraries and noticed that symbol in the error message is present in the device version but not the simulator version: 000229f4 D _OBJC_CLASS_$_OMAppMeasurement Anyone encountered similar problems? If any Omniture people read this: is there a chance of getting some dev's eyes on this to see if they can reproduce it? Thanks for any help / suggestions / etc. in advance! -Dave