Compare 2 Dates In VBA Code

I am getting a type mismatch error ehen comparing 2 dates. I tried entering all date formatting but it still throws the same error... here is my code. i have highlighted in bold where I get the error. the Error it throws is Run Time Error 13. Type Mismatch Error. I am using office excel 2003 SP3

Dim siebApp As SiebelWebApplication
Dim siebBusObj As SiebelBusObject
Dim revBC As SiebelBusComp
Dim isRecord As Boolean
Dim sRep As String
Dim sCompany As String
Dim sLocation As String
Dim sStep As String
Dim sProb As String
Dim sDate As String
Dim RetDate As Date
Dim CurDate As Date
Const DateCol = 9
CurDate = Now()
RetDate = Sheets("Users"). Cells(DateCol)
r = Sheets("Users").Cells(65536, 1).End(xlUp).Row 'Get next blank row
Sheets("Users").Cells(r, DateCol) = CurDate
'Create The Siebel WebApplication Object
Set siebWebApp = CreateObject("TWSiebel.SiebelWebApplication.1")...........................