xlsx file has error that file in use by another user

Hi ,
I am getting an error while browsing a xlsx file through my code in c#. 
I got the error , file in process , used by another user.
I'm  using gembox code not ms excel interop.
following is  my code lines where i get error:
ExcelFile ef =  new ExcelFile(); 
SpreadsheetInfo.SetLicense("XXXX-XXXX-XXXX-XXXX");
ef = ExcelFile.Load(this.m_filePath); 
Thank you..