Upgraded to SDK 4.1 and can no longer install on device with OS 4.0

Each time a new SDK came out, there has been the problem with the "Base SDK" which is really a "max SDK" and backward compatible. My project builds fine after adjusting the "Base SDK" in the Project Info.

But why do I 开发者_运维技巧get these messages on the console below the Target Info window when I change the "iOS Deployment Target" to iOS 4.0?

"iOS 4.0 - Code will not load on systems earlier than 4.0. [4.0]" and 
"iOS 4.1 - Code will not load on systems earlier than 4.1. [4.1]" 

The code did not change since the last successful install on iOS 4.0 under iOS 4.0 SDK.

The project builds without error, but the installation on the device (iOS 4.0) fails with

The Info.plist for application [path/to/app.app] specifies 
a minimum OS version of 4.1 which is too high to be installed
on [device].

But there is no mention of a minimum OS version in [project]-Info.plist.

Any ideas?

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Did you change the iOS Deployment Target in both your Project and Target Build Settings? If you only change the project setting, an old target setting will override it.