This is common. Its not telling you that you have no software on your phone, its telling you that there's no software on your computer that matches what you have installed on your phone. Perhaps you don't have the software installed on your computer anymore (or perhaps you never installed the handheld software there). Either way, you can go to C:\Program Files\Common Files\Research In Motion\AppLoader and delete a file called Vendor.xml from there. Open up Desktop Manager and Application Loader again and see if there's anything there now. If not, then go back to C:\Program Files\Common Files\Research In Motion\ and see if there is a folder called Shared. If not, then you do not have the handheld software installed on your Desktop and you won't have anything to worry about.
If you do not have it installed, then you can go download Cingular's version of the 7100 series software and install it.
https://www.blackberry.com/Downloads...E4F82F9F00E7D4
You will need to delete the Vendor.xml file from the location above after you install this.
One caveat may be that it will ask you to upgrade your handheld. You didn't list which model you have, so you may want to download the T-Mobile code from
www.t-mobile.com/bbupgrade and install it instead.
And if you have any 3rd party software installed, and its not showing up in Application Loader, thats because you deleted the installation files from where you originally loaded the software from.