Hi Webster Velasco,
Please make sure that the upload is not inside RadAjaxPanel/UpdatePanel or ajaxified with RadAjaxManager. RadUpload cannot upload files using AJAX calls. This is a limitation of the XmlHttpRequest component, used in all AJAX frameworks for asynchronous calls to the application. In order to upload a file your application must perform a full page postback. More information on how to workaround this problem can be found here.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items