rp.GetRouteBetweenPoints(gpsMarker.Position, gpsMarker.Position, False, False, CInt(mainMap.Zoom))
As far as I can tell you set a route from gpsMarker
to itself.
If you want to route a travel that goes through each point in gpsDtable.Rows
then you can just connect each marker with a previous one. Something like this:
'DISCLAIMER: untested code
Dim rp As RoutingProvider = TryCast(mainMap.MapProvider, RoutingProvider)
Dim previousGpsMarker As GMapMarker_Custom
For Each dtrow In gpsDtable.Rows
gpsMarker = New GMapMarker_Custom(New PointLatLng(dtrow("Latitude"), dtrow("Longitude")), "vistaMarker")
routes.Markers.Add(gpsMarker)
'If it's not a starting point
If previousGpsMarker IsNot Nothing Then
'Set a route from previous marker
Dim route As MapRoute = rp.GetRouteBetweenPoints(previousGpsMarker.Position, gpsMarker .Position, False, False, CInt(mainMap.Zoom))
Dim r As New GMapRoute(route.Points, "")
routes.Routes.Add(r)
End If
'Storing the previous marker
previousGpsMarker = gpsMarker
Next