ExcelBuffer.SelectSheetsNameStream(NVInStream) throwing error

Hi Expert,

I am trying to upload data from excel file and written below code

        DialogCaption := 'Select File to upload';
        UploadResult := UploadIntoStream(DialogCaption, '''', Name, NVInStream);

        If Name <> '' then
            Sheetname := Rec_ExcelBuffer.SelectSheetsNameStream(NVInStream)
The bold highlighted one throw below error. Can any one let me know what wrong with this? This code was working fine earlier. I am kind of clueless any suggestion please