It sounds like your Exchange Server requires a certificate. This is a copy of a reply of mine from another post dealing with a similar problem. The user said it worked for him.
how to connect through wireless internet
I found this in my travels... It's not for newbies but ask if you have problems. Follow the instructions to the T. This is what you need to do to make your Axim wireless work on your campus.
from
http://msgoodies.blogspot.com/2005/1...-own-root.html :
"First you need to get a copy of regeditSTG.exe (Apparently a HTC signed registry editor with an issuer CN that equals HTCCanary) zip it and move it to your device (You get an error if you copy the .exe directly). Now unzip it by double clicking it from File Explorer (on your device) and run the program. Then change the Grant Manager Policy registry key (Remember to note the old value) -
HKLM\Security\Policies\Policies\00001017 = 144
After setting the registry key above reboot your device, copy your root certificate to the File Explorer and click to install it (There’s no feedback that the operation was successful – check settings, security, certificates, root certificates for the existence of your certificate).
Before proceeding, we choose to set the registry setting back to the original values so the Phone was once again protected and finally Exchange ActiveSync and WPA worked like a charm ;-)
The solution apparently works on several different devices like i-Mate, C550, Qtek 8310 (Thats the only one we tested - don't ask about the others but do feel free to comment on those that works ;-) and probably most Windows Mobile 2005 Smartphone devices.
A utility called SDA_ApplicationUnlock.exe can also be found on the Internet but our testing shows us that it does the same as the Grant Manager Policy registry key. The problem with this application is that it only has a "Remove Lock" feature and no "Enable Lock" feature. Different posts/websites show the solution for other phones that include the use of SDA_ApplicationUnlock.exe utility; so if you run into problems you might want to try it."