Listbox error

I have the following list of layers

!layerlist
("0" "aaaa" "bbbb" "cccc" "dddd" "ffff" "hhhh" "xxxxx" "zzzzz")

Command: (type layerlist)
LIST

I attempt to add the list to the list box using the following code

(defun c:Nortec_Layer_Control_Form1_GraphicButton12_OnClicked (/)

  (dcl_Form_Show Nortec_Layer_Control_Form2)

  (dcl_ListBox_AddList Nortec_Layer_Control_Form2_ListBox1 layerlist)  

)

I get a runtime error:
Error: NIL value not allowed
Function: dcl_listbox_addlist
Argument 0

Any ideas what I am doing wrong?

Thanks

Scott

Scott, if this is a modal form then the (dcl_ListBox_AddList) function will not execute until after the form is closed and the value of Nortec_Layer_Control_Form2_ListBox1 is set back to Nil.  Instead, put that code in an OnInitialize event handler and enable the OnInitialize event for the form.

Thanks Owen,

I hope I can keep the questions to a minimum. I appreciate the help, and hopefully others can lean from my attempts as well ;D

Cheers

Scott