PDFsharp & MigraDoc Foundation

The code in question is:

string path = System.IO.Path.GetTempPath() + Guid.NewGuid().ToString() + ".pdf";
MemoryStream msPDF = new MemoryStream(fileBytes);
PdfSharp.Pdf.PdfDocument pdfDoc = PdfReader.Open(msPDF, PdfDocumentOpenMode.ReadOnly);

The fileBytes variable gets passed from a FileUpload control and the file being uploaded is a valid PDF.

The last line throws the following error:

[FormatException: Input string was not in a correct format.]
System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal) +7471623
System.Number.ParseInt64(String value, NumberStyles options, NumberFormatInfo numfmt) +130
PdfSharp.Pdf.IO.Lexer.ScanNumber() +323
PdfSharp.Pdf.IO.Lexer.ScanNextToken() +152
PdfSharp.Pdf.IO.Parser.ReadSymbol(Symbol symbol) +19
PdfSharp.Pdf.IO.Parser.ReadTrailer() +81
PdfSharp.Pdf.IO.PdfReader.Open(Stream stream, String password, PdfDocumentOpenMode openmode, PdfPasswordProvider passwordProvider) +243
PdfSharp.Pdf.IO.PdfReader.Open(Stream stream, PdfDocumentOpenMode openmode) +10
BEEMarketplace.Business.OrderDocument.Upload(Byte[] fileBytes) +305
BEEMarketplace.UI.Controls.OrderDocuments.btnUpload_Click(Object sender, EventArgs e) +54
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565


Can someone help me?