Custom button to launch Part Tracker

I'm trying to code a button (on a handheld screen) to launch part tracker and pass the part number on the screen to the part tracker form. I am able to launch the tracker but its not bringing in the part number.

Here is the code so far:

Private Sub btnPartTracker_Click(ByVal Sender As Object, ByVal Args As System.EventArgs) Handles btnPartTracker.Click

Dim partNum as EpiTextBox = CType(csm.GetNativeControlReference("8f54f627-4a40-4e54-8a2a-fe39fccf325f"), EpitextBox)
Dim lfo As LaunchFormOptions = New LaunchFormOptions()
lfo.ValueIn = partNum.text
ProcessCaller.LaunchForm(MtlMoveForm, "Epicor.Mfg.UI.HHPartTracker", lfo)

End Sub

Does anyone have any experience with this?