Here is my code to drop it onto the page:

             <CuteWebUI:Uploader
                MaxFilesLimit="20"
                MaxFilesLimitMsg="Please Upload max 20 files at once"
                ID="fileUploaderAjax"
                ManualStartUpload="true"
                InsertText="Select files(s) to upload"
                OnFileUploaded="Uploader_FileUploaded"
                OnUploadCompleted="Uploader_UploadCompleted"
                CancelText="Cancel"
                CancelUploadMsg="Cancel"
                FileTooLargeMsg="File exceeds max. size limit: 50Mb"
                CancelAllMsg="Clear upload list"
                MultipleFilesUpload="true"
                UploadingMsg="Uploading.."
                runat="server">
                <ValidateOption AllowedFileExtensions="doc,docx,xls,xlsx,pdf,ppt,txt,rtf,gif,bmp,tiff,jpg,jpeg,zip,rar,tar.gz" />
                <CancelButtonStyle CssClass="ajaxUploader" />
                <InsertButtonStyle CssClass="ajaxUploader" />
                <ProgressLabelStyle CssClass="ajaxUploader" />
            </CuteWebUI:Uploader>

Its inside an asp:Panel which is initiall hidden - if that makes a difference?