System.Nullable.FromObject - Not valid with VS 2005

I was previously using VS 2005 Beta 2 and just upgraded to the released version of VS 2005 Pro.  Everything seems to work fine except for 2 forms (out of 30).   After opening my project in VS I attempted a build and it came back with an error.  There were no errors the last time I worked with the Beta version.   The error is in the Designer file for the form.   Here's the code in question:

Public Overloads Overridable Function Fill(ByVal dataTable As SelectMemberHarvestPlanVolume.usp_SelectMemberHarvestPlanVolumeDataTable, ByVal harvestPlanID As System.Nullable(Of System.Guid)) As System.Nullable(Of Integer)
            Me.Adapter.SelectCommand = Me.CommandCollection(0)
            If (harvestPlanID.HasValue = true) Then
                Me.Adapter.SelectCommand.Parameters(1).Value = CType(harvestPlanID.Value,System.Guid)
            Else
                Me.Adapter.SelectCommand.Parameters(1).Value = System.DBNull.Value
            End If
            If (Me.m_clearBeforeFill = true) Then
                dataTable.Clear
            End If
            Me.Adapter.Fill(dataTable)
            If ((Me.Adapter.SelectCommand.Parameters(0).Value Is Nothing)  _
                        OrElse (Me.Adapter.SelectCommand.Parameters(0).Value.GetType Is GetType(System.DBNull))) Then
                Return System.Nullable.FromObject(Of Integer)(Nothing)
            Else
                Return New System.Nullable(Of Integer)(CType(Me.Adapter.SelectCommand.Parameters(0).Value,Integer))
            End If
        End Function

The problem is with "System.Nullable.FromObject".  VS says that "FromObject is not a member of System.Nullable".  

What needs to be changed to get this to work?

Thank you in advance.