Thanks for your attention.

// The binary value adding part.

    // szTmpFile is a character array which contains the name of resource
file .

    theTags.AddBinary("BinaryData",szTmpFile);

// The binary value reading part.

    LPBYTE pData = (LPBYTE) theTags.BinaryValue("BinaryData");

    //returns the stored tag;The above code will return the correct value
    // if it is taken before the presentation is closed,
       // the same code will return 'null' if the value is read after
the presentation
       // is opened after saving and closing it.

The problem is happening in presentations if we save presentations in
the .pptx extension in Office 2007. The problem is not occuring in
presentations saved in .ppt format in Office 2007.