       when "is not equal to"
         if value != answer then hide_questions = false
       when "is empty"
-        if value.length < 1 then hide_questions = false
+        if value.length && value.length < 1 then hide_questions = false
       when "is not empty"
-        if value.length > 0 then hide_questions = false
+        if value.length && value.length > 0 then hide_questions = false
       when "is greater than"
         if $.isNumeric(value)
           if parseFloat(value) > parseFloat(answer) then hide_questions = false

          if value != answer
            hide_questions = false
        when "is empty"
          if value.length < 1
            hide_questions = false
        when "is not empty"
          if value.length > 0
            hide_questions = false
        when "is greater than"
          if $.isNumeric(value)

        else
          return selected.val()
      else
        return
    if $conditionElement.is(":checkbox")
      if $conditionElement.is(":checked")
        if $conditionElement.attr('data-label-value')
