Event macro error when opening workbook

Hello,

I am a newbie excel visual basic program dabbler. I have created a macro that runs several other macros just fine when I run it myself. I have been attempting to set this macro up to run automatically when the workbook is open. I am using excel 2004 for Mac. I go under tools, macro, visual basic editor and then in the Projects window under Objects select this worksheet. Then under the workbook tab I put this code:

Private Sub Workbook_Open()
AllBilling
End Sub

The macro AllBilling is under the modules folder. I can not figure out for the life of me what the problem is here. I get the compile error: expected variable, procedure, not module. This may be really simple, but again I am so very green and teaching myself. Beating head up against wall for two days. Can anyone help me?
J