textchanged event is not firing in textbox.

Question

Please help me this is my code

 

Code Behind:

protected void txtPincode_TextChanged(object sender, EventArgs e)

{

try

{

TextBox lsender = (TextBox)sender;

if (lsender.Text.Contains("(") && lsender == txtPincode)

{

lsender.Text = lsender.Text.Split('(')[1].Replace(")", "");

}

}

catch (Exception exp)

{

Log.writeLog(exp);

}

}

.aspx code:

 

<asp:Label ID="lblPincode" runat="server" Font-Size="Small" Text="Pincode" Font-Bold="true"></asp:Label>