Loading Longitude

Hi there

I am trying to load the longitude from a GPS receiver onto an image. I encounter some problems with the following source code. It always returns a runtime error msg(Open failed.Error unknown) pointing to the syntax "GTrack.Open".
Pls help

Below is my source code

Private Sub cmbGPSOpen_Click()
' specify the communications settings
GTrack.Type = GTRACK_NMEA
GTrack.BaudRate = GTRACK_4800
GTrack.DataBits = GTRACK_8
GTrack.StopBits = GTRACK_1
GTrack.Parity = GTRACK_NONE

' Poll specifies rate of output
' data from GPS receiver.
GTrack.PollRate = 1 ' one poll / 1 second
' Open the communication to the GPS receiver or
' the playback file.
lblLongitude.Caption = Format(dLongitude, "###0.000000")
GTrack.Open
End Sub
Private Sub GTrack_Longitude(ByVal dLongitude As Double)
lblLongitude.Caption = Format(dLongitude, "###0.000000")

End Sub

:confused: