Input string was not in a correct format

I use this below code in .aspx file for delete Girdview row.

Asp Code:

Delete

C# Code

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)

{

if(e.CommandName == "DeleteRow")

{

SqlConnection cs = new SqlConnection("Data Source=DESKTOP-3T94FQ0;Initial Catalog=RAMS;Integrated Security=False;UID=sa;Password=sa123;");

SqlCommand deleteCommand = new SqlCommand("DELETE FROM [tbl_musannet] WHERE [mus_id]= @mus_id",cs);

deleteCommand.Parameters.Add("@mus_id", SqlDbType.BigInt).Value = Convert.ToInt64(e.CommandName);

cs.Open();

deleteCommand.ExecuteNonQuery();

cs.Close();

}

But when I going to delete rows "Input string was not in a correct format" error is showing.

Please help.

Thanks