Click event on an ImageButton Column

Hi

I have a DataGrid with an ImageButton column. When I click on an imagebutton I get a postback but it doesn't run the OnImgBtnClick method. I can actually comment out the line where I add this Click event to the ImageButton Column and it makes no difference, I still get a postback. This is driving me crazy...something seems to be causing an OnClick postback and it isn't my Click event
I've included the code below....any help will be much appreciated as I've been looking at this for a long time and I'm havnig a real problem understanding what's going on

Thanks in advance, John

private void OnImgBtnClick(object sender, EventArgs e

label1.Text="Button Clicked"


public void BindDataGrid(string querytype