Android Question Problems with in app purchses

(in starter module)
Sub CheckForGooglePlayServices As Boolean   
    Try
    Dim GoogleApiAvailablity As JavaObject
    GoogleApiAvailablity = GoogleApiAvailablity.InitializeStatic("com.google.android.gms.common.GoogleApiAvailability").RunMethod("getInstance", Null)
    Dim context As JavaObject
    context.InitializeContext
    If 0<> GoogleApiAvailablity.RunMethod("isGooglePlayServicesAvailable", Array(context))  Then
        GoogleApiAvailablity.RunMethod("makeGooglePlayServicesAvailable", Array(context))
        Return False
    End If
    Return True
    
    Catch
        Return False
    End Try
End Sub

 Sub RestorePurchases
    
    If CheckForGooglePlayServices Then
    
    billing.Initialize("billing")
    Wait For (billing.ConnectIfNeeded) Billing_Connected (Result As BillingResult)
    If Result.IsSuccess Then
        Wait For (billing.QueryPurchases("inapp")) Billing_PurchasesQueryCompleted (Result As BillingResult, Purchases As List)
        'Log("Query completed: " & Result.IsSuccess)
        If Result.IsSuccess Then
            Dim found As Boolean=False
            For Each p As Purchase In Purchases
                If p.Sku = Main.productid Then
                    found=True
                    HandleAdsPurchase(p,"restorepurchases")
                End If
            Next
            
            If found=False Then
            CallSub(Main,Main.revokesub)
            End If
            
        End If
    End If
    End If
End Sub

(in main)

Sub startbilling
    
    Wait For (Starter.billing.ConnectIfNeeded) Billing_Connected (Result As BillingResult)
    If Result.IsSuccess Then
        'get the sku details
        Dim sf As Object = Starter.billing.QuerySkuDetails("inapp", Array(productid))
        Wait For (sf) Billing_SkuQueryCompleted (Result As BillingResult, SkuDetails As List)
        If Result.IsSuccess And SkuDetails.Size = 1 Then
            'start the billing process. The PurchasesUpdated event will be raised in the starter service
            Dim sku As SkuDetails=SkuDetails.Get(0)
            Result = Starter.billing.LaunchBillingFlow(sku)
            If Result.IsSuccess Then
                        
                        
                Return
            End If
        End If
    End If
    ToastMessageShow("Error starting billing process", True)
    
End Sub