Unable to resolve the error in IronPython script embedded in Spotfire -

hi new python , spotfire. unable resolve below error.
code

import system system.io import filestream, filemode spotfire.dxp.application.visuals import tableplot  spotfire.dxp.data.export import datawritertypeidentifiers import clr clr.addreference("system.windows.forms") system.windows.forms import savefiledialog   savefile = savefiledialog()   #gets file path user through filedialog savefile.filter = "xls format (*.xls)|*.xlsx|*.xls|*.xlsx" savefile.showdialog() savefilename = savefile.filename print "savefilename=", savefilename stream = filestream(savefilename, filemode.create) #export table data file viztable.as[tableplot]().exportdata(datawritertypeidentifiers.excelxlsxdatawriter, stream) stream.dispose() 

when run above code below error.

system.missingmemberexception: 'nonetype' object has no attribute 'exportdata' 

the above code used export data excel sheet using spotfire tool. please suggest me

viztable empty because in order have spotfire populated/initialized

you have add parameter script - in example below such parameter called myvisual - after added can used in code