File Upload For Microsoft Office 2007 Document

Hi all,
I have face so problem and hope anyone can help me
- I have develop a web application which allow user to upload the microsoft office 2003 document (eg .doc, .ppt, .xls, ...)
- But i have found that it will prompted error when user upload microsoft office 2007 document (eg .docx, ...)
- My current code:
HttpPostedFile myFile = FileUpload1.PostedFile;
byte[] yData = new byte[myFile.ContentLength];
string filename = Path.GetFileName(myFile.FileName);
myFile.InputStream.Read(myData, 0, myFile.ContentLength); 
- Can anyone tell me how to modify my code to upload the microsoft office 2007 documents?
Thank in advance
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