Call Child Action Failed -- No Doing without error

 Dear all,
 
I have the below code. When in the first time go to the if statement and return is executed. It will remain in this form. But later when return is not reached after several save button is clicked ( if statement is false), CallChildAction has not done anything without prompting error. It should return to previous form with refreshing the previous form. Do you have this experience and Do you know how to fix?? 
 
protected void btnSave_Click(object sender, EventArgs e)
{
 if( .....)
  return;
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "call_parent_refresh", "CallChildAction('" + Request.QueryString["chld_id"].ToString() + "');", true);
}
...