cf error

My code was working fine and then all of a sudden this morning, I get the error below and it's very frustrating.
I can't figure it out.
Please HELP!
Thanks. :)

Error Occurred While Processing Request  
Element HLS.FIRST_NAME is undefined in SESSION.  
 
 
The error occurred in C:\CFusionMX\wwwroot\CFIDE\Isaac_Stage\specailReg\specialVol.cfm: line 138
Called from C: line -1
Called from C:\CFusionMX\wwwroot\CFIDE\Isaac_Stage\specailReg\specialVol.cfm: line 131
Called from C:\CFusionMX\wwwroot\CFIDE\Isaac_Stage\specailReg\specialVol.cfm: line 126
Called from C:\CFusionMX\wwwroot\CFIDE\Isaac_Stage\specailReg\specialVol.cfm: line 1
 
136 :         <td width="173" height="26">First Name:</td>
137 :         <td width="150"><cfinput name="FIRST_NAME"
138 :                                            value="#SESSION.HLS.FIRST_NAME#"
139 :                                        size="25"
140 :                                            message="First Name is required">
 

My piece of the code:
<CFIF NOT IsDefined("SESSION.HLS")>
      <CFSET SESSION.HLS = StructNew()>
      <!-- Represents current page.-->
      <CFSET SESSION.HLS.StepNum = 1>
      
      <!-- Assign user entries to the structure for the first page. -->
      <CFSET SESSION.HLS.FIRST_NAME = "">
</CFIF>
<CFIF IsDefined("form.FIRST_NAME")>
      <CFSET SESSION.HLS.FIRST_NAME = "#form.FIRST_NAME#">
</CFIF>


    <tr>
        <td width="173" height="26">First Name:</td>
        <td width="150"><cfinput name="FIRST_NAME"
             value="#SESSION.HLS.FIRST_NAME#"
             size="25"
             message="First Name is required">
        </td>
     </tr>