How to put this validation on asp.net file upload control?
<p>I have a fileUpload User Control FileUploadControl.ascx containing asp.net fileupload control and a requiredfield validator.</p>

<p>I have another usercontrol RenderingTemplate.ascx that contains two FileUploadControl.ascx.</p>

<p>RenderingTemplate.ascx is on page RenderingTemplateDetails.aspx, this page has save and cancel button.</p>

<p>Now My requirement is in case user selects a file in one fileupload control,he has to select in other as well. If he does not select any file,let postback happen.</p>

<p>I cannot use Requiredfieldvalidator as it fires for both. I tried adding onclientclick to page save button and check whether file upload has some text in it.but i didnot succedd.</p>

<p>Now i want this functionality to be a part of control so that i dont have to recode it on every page. IS there any clientside event on usercontrol which fires when save button of page is clicked. Please help and suggest some solution.</p>
