Call javascript from code behind c# sharepoint 2010 -

i have code in .ascx.cs file calls new page on href.

lblvideoassessment.text = "<a href='../sitepages/assessment.aspx?cat=" + cat + "' height='300px' width='300px' target='_blank' cssclass='icondisplaycss'><img src='~/_layouts/images/assessment.png' border='none'/></a><br/>" + cat; 

i want replace code javascript popup page change , feel.i want make page popup have written javascript method in .ascx file given below:

<script type="text/javascript">     function opendialog(url) {         var newpopup = sp.ui.$create_dialogoptions();         newpopup.url = url;         newpopup.width = 700;         newpopup.height = 350;         sp.ui.modaldialog.showmodaldialog(newpopup);     }  </script> 

i have called javascript in code behind , not work:

lblvideoassessment.text = "<a onclick='javascript:opendialog('../sitepages/quiz.aspx')' height='300px' width='300px' target='_blank' cssclass='icondisplaycss'><img src='~/_layouts/images/assessment.png' border='none'/></a><br/>" + cat; 

please advice do. same works fine sharepoint designer. please how pass javascript method on onclick.

it sounds want html assigning lblvideoassessment.text placed in page, is. that, <asp:label ... /> not right type of control use.

instead, want <asp:literal ... />. assignment same have:

litvideoassessment.text = "<a onclick='javascript:opendialog('../sitepages/quiz.aspx')' height='300px' width='300px' target='_blank' cssclass='icondisplaycss'><img src='~/_layouts/images/assessment.png' border='none'/></a><br/>" + cat;