Hi Gary,
I thinking you have not problem with header class. I thinking your grid have default COLUMN object. You must setup MemberClass and MemberClassLibrary for Grid object and be sure about class of column object.
here is little code block:



PUBLIC goForm
goForm = CREATEOBJECT("spForm")
goForm.Show()

DEFINE CLASS spForm As Form
ADD OBJECT Grid1 As spGrid
ENDDEFINE

DEFINE CLASS spGrid As Grid
MemberClass = "spColumn"
MemberClassLibrary = "c:\program1.prg"
ENDDEFINE

DEFINE CLASS spColumn AS Column
HeaderClass = "spHeader"
HeaderClassLibrary = "c:\program1.prg"
ENDDEFINE

DEFINE CLASS spHeader AS Header
PROCEDURE Click
=MESSAGEBOX("Header Click")
ENDPROC
ENDDEFINE