You cannot directly refer to the image control which is inside the datagrid, you have to first find the control, cast it and then set the src, may be you can do it in the ItemDataBound event as below:
if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
imgShopping = (HtmlImage) e.Item.FindControl("Image1");
imgShopping.Src = "abc.jpg";
Fortune favours the brave, so don't regret on missed oppurtunities.