As the FormView uses templates which are populated when data is bound, you can only grab your control on the DataBound event like so:
protected void Page_Load(object sender, EventArgs e)
{
FormView frmYorumAt = (FormView)loginYorumAtView.FindControl("frmYorumAt");
frmYorumAt.DataBound += new EventHandler(frmYorumAt_DataBound);
}
void frmYorumAt_DataBound(object sender, EventArgs e)
{
FormView formView = sender as FormView;
// Let's make sure the InsertItemTemplate is actually being run, otherwise
// the LinkButton won't exist.
if (formView.CurrentMode == FormViewMode.Insert)
{
LinkButton btnYorumAt = (LinkButton)formView .FindControl("btnYorumAt");
// Do whatever you need to do with the LinkButton here.
}
}