Null reference exception while using item template controls in datalist

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C#

Hi, I have used datalist to display data from the table. In each record there is textbox and save button. When user enter data in textbox and click save, the data should be inserted in other table with the id of that row as foriegn key. But, when I take the value of textbox in another variable, the nullreferrenceexception occurs. I write following line to check the value of textbox.

Label1.Text=((Label)dlProductBasedSales.FindControl("lblIProductId")).Text;

What is wrong? Suggest me the solution.