Flash builder error - namespace

I have some project files, in which I have changed the air version 1.0 to 2.5, because I have the air 2.5. But it is not compiling. It shows error that it cannot create air http://ns.adobe.com/air/app开发者_开发问答lication/2.5.

Please help.

Besides the AIR runtime you must also have

1. the Air SDK (available here), or the new Flex Hero SDK (dev.) which is bound with air2.5
2. configure your compiler to use this new SKD to build your project.

Id suggest you to use the (currently latest) Flex Hero SDK, which contains the air 2.5 runtime, so you don't have to bother merging your flex and new air sdks manually.
Inside your IDE you specify a new Flex SDK to point to the Hero installation, and compile your project using this.