Shannon and Khushi,
The bigest thing is to ensure that you do not have to AGS Flex libs specified or linked in your project. Check the libs folder and ensure you only have one agslib-x.x-xxxx-xx-xx.swc in that folder and in the projects properties go to the Flex Build path and ensure in the Library path that there is not a linked agslib-x.x-xxxx-xx-xx.swc there if you do have one in the libs folder.