Excel Export: The Controls collection cannot be modified because the control contains code blocks

Thanks again Mudassar for all of your help.  The code on one of my aspx pages is giving me this error:

I'm getting this on the code behind for export to excel on one of my pages.

The Controls collection cannot be modified because the control contains code blocks (i.e. <% ... %>). It is referring to this line Me.GridView1.Parent.Controls.Add(frm)

I have this code in the aspx page.  I am using two gridviews.  I need to have this on the page any way I can fix the code so I can use that export to excel you created?

  <% If(Session("PendingClaims"))%> then display gridview1 <%Else%>

Then display gridview2 <% End If %>