Forms Data Controls :: Disabling Validation For Edit Button In Grdiview?

I want to disable validation for asp:command field Edit button for some rows.How do i that?

Here is the asppx code :

<asp:CommandField HeaderText="Actions" ButtonType="Link" DeleteText="Delete" ShowDeleteButton="True"
EditText="Edit" ShowEditButton="True" CausesValidation="true" />

Here is what am trying to do in greiview itemdatabound event:

if (e.Row.RowType == DataControlRowType.DataRow)
{
LinkButton btn = (LinkButton)e.Row.Cells[2].Controls[0];
if(btn!=null)
{
btn.CausesValidation=false; //gives error
}
}