JQuery IF statement issue

JQuery IF statement issue

i have this JQuery code,
  2. if ($('#lblProteinsApoklisi').val() >= 0) {
  3.                     $('#lblProteinsApoklisi').addClass('UnderStats');
  4.                 }
  5.                 else {
  6.                     $('#lblProteinsApoklisi').addClass('OverStats');
  7.                 }
if the textbox has a negative number i just put a background color of red, else a background color of red. No errors are shown but the .addClass doesnt seem to work. Thanks in advance.