>>May be because it's the Assembly file and the dialog looks for dll/exe files?
>
>If you have the code you could build a .dll or .exe?
>
>Alternatively, you could click on the combo box that specifies .dll/.exe files and then choose "all files".
>
>Do you have the "trial" versions of these DevExpress controls?
>
>Dave.

I don't know where these controls come from. May be I downloaded them and install, may be the previous developer did. In any case, they are Windows Controls, not Web Controls thus I didn't see them.

BTW, after I added my custom class and added it to the Web page, I'm now getting errors related to AJAX.

I'm guessing the custom controls were build using the previous version of Web.Extensions, I would have to go to that project and re-build, I guess.