Null dates in Insert Into statement

Hi

I'm trying to execute the following code:

    sSQL = "insert into lkpChanges
(SiteRef,ProjectName,InvestmentType,FieldChanged,PreviousDate,NewDate,ChangeDate,CurrentRelaunch)
" & _
            "values (" & sRef & ", """ & pName & """,""" & iType &
""",""" & fChange & """," & IIf(IsNull(pDate), Null, pDate) & "," &
IIf(IsNull(txtFSOS), Null, txtFSOS) & "," & Date & "," &
IIf(IsNull(txtFRelaunch), Null, txtFRelaunch) & ");"

    DoCmd.RunSQL sSQL

which evaluates to:

insert into lkpChanges
(SiteRef,ProjectName,InvestmentType,FieldChanged,PreviousDate,NewDate,ChangeDate,CurrentRelaunch)
values (572, "Accrington","New","SOS",,02/01/2008,30/05/2008,);

However, i get the message "Syntax error in Insert Into statement"

I presume this is due to the null dates. Is there anyway around this?

Thanks
Paul