barcode font problem

I want to have barcode to be sent to client through ASP.NET. I have the bar code...I am making a dynamic gif out of it....but the font is not displaying any barcodes....but the barcode font works very fine in MS-OFFICE suite....the following is the code I have written.....

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Dim img As New Bitmap(width, height, PixelFormat.Format24bppRgb) 'letter size

Dim font As New Font("EAN-13", 18, FontStyle.Regular)
Dim g As Graphics = Graphics.FromImage(img)

g.FillRectangle(New SolidBrush(Color.White), 0, 0, width, height)
g.DrawString("1 0 1 1 100111011 10457", font, New SolidBrush(Color.Black), 10, 10)
Response.ContentType = "Image/gif"
img.Save(Response.OutputStream, ImageFormat.Gif)
img.Dispose()
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urgent....please anyone