PC SDK Writing to RAPID data

Hello everybody,
I have question abort developing the pc sdk application.I use VB.net,how can i writing to rapid data.
HELP ME PLS
my code:

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

Dim rapidBool As ABB.Robotics.Controllers.RapidDomain.Bool

Dim rd As ABB.Robotics.Controllers.RapidDomain.RapidData = controller.Rapid.GetRapidData(“T_ROB1”, “MainModule”, “i”)

rapidBool.Value = False

Me.master = Mastership.Request(Me.controller.Rapid)

rd.Value = rapidBool

Me.master.Dispose()

'Dim rapidBool As ABB.Robotics.Controllers.RapidDomain.Bool

Dim aTool As ToolData

Dim aPos As New Pos()

aPos.FillFromString(“[2,3,3]”)

aTool.Tframe.Trans = aPos

Using Mastership.Request(controller.Rapid)

rd.Value = aTool

End Using

End Sub

ERROR: Me.master = Mastership.Request(Me.controller.Rapid)
show at vb.net = GenericControllerException was unhandled

what do i do wrong