<PDA application> is not a valid Pocket PC application (Pocket PC, PDA Module)
This error occurs if you build a PDA application for a processor that differs from the PDA target or if the PDA application is unable to load required DLLs or libraries.
To correct this error, verify the processor selected in the PDA Build Specification Properties dialog box matches the processor of the PDA target. Also, verify the PDA target contains the required DLLs.