Cannot EXport Chart Twice(Interop.Excel) c#.Net VB.NET, ASP.NET

Question

EXCEL INTERLOP CHART ERROR C# - A share violation has occurred. (Exception from HRESULT: 0x80030020 (STG_E_SHAREVIOLATION))

Please download the file attached 

When I press Button1 twice I get the error
A share violation has occurred. (Exception from HRESULT: 0x80030020 (STG_E_SHAREVIOLATION))
 
Please help me solve this issue.