Variable LNAME is Undefined

Hi. I have these 2 pieces of code, and when I run the page, I keep getting VARIABLE LNAME IS UNDEFINED. Can someone please help? Thanks!

<cfquery name="TeacherFN" datasource="AITE_Test_System">      SELECT Lname, Fname     FROM dbo.[Teachers]     WHERE AD_Username = '#FORM.TeacherAD_Username#' </cfquery> <cfquery name="ClassEdit" datasource="AITE_Test_System"> <cfif #FORM.EditMode# IS "AddClass">      INSERT INTO dbo.[Classes] (Class_Name, Teacher_lname, Teacher_fname, Teacher_AD_Username, Period) VALUES ('#FORM.ClassName#', '#Lname#', '#Fname#', '#FORM.TeacherAD_Username#', '#FORM.Period#') <cfelseif #FORM.EditMode# IS "EditClass">      UPDATE <cfelseif #FORM.EditMode# IS "DeleteClass">      DELETE FROM dbo.[Classes] WHERE Fname='#Fname#' AND LName='#Lname#' AND AD_Username='#FORM.AD_Username#' </cfif> </cfquery>

I am running this with #FORM.EditMode# IS "AddClass">