Automated Content Updating - Comparing DateTime

I'm working on a automated content updating script. When a new update is entered I insert into a database table, and cache, the time of the update.
Dim setT As DateTime = DateTime.Now
modCommand2.Parameters.Add("?brmt", setT)
modCommand2.Parameters.Add("?lup", setT)
'databse code here
Dim myData As String = CType(Cache("ltu"), String)
' if it's not there, add it
If myData Is Nothing Then
Cache("ltu") = setT
Else
Cache.Remove("ltu")
Cache("ltu") = setT
End If