I can only see (or suggest) one thing here,
lblResult.Text = productModel.InsertProduct(product);
The
InsertProduct
function must return a
string
value, because the
Text
property of
Label
objects has a type of String, so either do that, or call a ToString function on the result, like,
lblResult.Text = productModel.InsertProduct(product).ToString();
Secondly, from wherever you captured that code, you need to ask them why they wrote it this way. Also, you can change the code to the following one and would be a better approach,
productModel.InsertProduct(product);
lblResult.Text = "Product added."
Much simple, and a better UX as well!