Although I am not 100% sure I believe that windows mobile aplications will almost certainly not work on windows ce but only on windows mobile itself. Infact I think that the application you are trying to run must be made for that specific version of windows ce. I know people over at the cowon forum have been having problems running certain applications on their Q5's (windows ce 5.0 based) as the apps were made for the wrong version of windows ce (I believe their are is more than 1 version eg. standard, professional etc). Wikipedia has a bit about it:
Pocket PC and Windows Mobile is a Microsoft-defined custom platform for general PDA use, and consists of a Microsoft-defined set of minimum profiles (Professional Edition, Premium Edition) of software and hardware that is supported. The rules for manufacturing a Pocket PC device are stricter than those for producing a custom Windows CE-based platform. The defining characteristics of the Pocket PC are the digitizer as the primary Human Interface Device and its extremely portable size.
Windows CE - Wikipedia, the free encyclopedia