please help.. i got problem in c# code.. really need help.. :'(

privatevoid textBox4_TextChanged(object sender,EventArgs e){double rank;if(Double.TryParse(textBox4.Text,out rank)){if(rank <TimeSpan.Parse("00:00:15.200").TotalMilliseconds){ textBox5.Text="Excellent";}elseif(rank >=TimeSpan.Parse("00:00:15.200").TotalMilliseconds&& rank <TimeSpan.Parse("00:00:16.100").TotalMilliseconds){ textBox5.Text="Above Average";}elseif(rank >=TimeSpan.Parse("00:00:16.200").TotalMilliseconds&& rank <TimeSpan.Parse("00:00:18.100").TotalMilliseconds){ textBox5.Text="Average";}elseif(rank >=TimeSpan.Parse("00:00:18.200").TotalMilliseconds&& rank <TimeSpan.Parse("00:00:19.300").TotalMilliseconds){ textBox5.Text="Below Average";}elseif(rank >=TimeSpan.Parse("00:00:19.300").TotalMilliseconds){ textBox5.Text="Poor";}else{ textBox5.Text="Unknown - Error";}}}
i already did this for my code.. but the problem occurred when my text5.text remained blank.. i did try to put it in button but no luck.. it remained the same.. really.. please help..