using a function getting  BC30451 error

I'm still coding in VS 2003, ASP.NET 1.1 because I work in the public sector and we have no money for training. I have one line of code, that calls one function that already works perfectly in other applications, but I cannot find one difference to figure out why it's not working here. The code uses a function to return an image.

The .apsx page reads:
<asp:Image Runat="server" Width="100" AlternateText="Photo Unavailable" ImageUrl='<%# GetImg(Container.DataItem("ImageID")) %>' ID="Image1" ></asp:Image>

The Function looks like this:
    Public Function GetImg(ByVal sImg As Object) As String
        Try
            With sImg
                If sImg Is DBNull.Value Then
                    sImg = "Imgs\nophoto.gif"
                Else
                    sImg = "http://www.hcso.org/Records/Images/" & sImg & ".jpg"
                    'Response.ContentType = "image/jpeg"
                    'Response.BinaryWrite(sImg)
                    'Response.End()
                End If
            End With
            Return sImg
            lblError.Text = sImg
        Catch ex As Exception
            lblError.Text = ex.ToString
        End Try
    End Function


Does anyone see any reason why this would not work like in the other apps???
Thank you!