Sorting method for Excel in vb.net -

i trying sort range in excel within code in vb.net (visual studio).the error message saying: unhandled exception of type 'system.runtime.interopservices.comexception' occurred in microsoft.visualbasic.dll additional information: reference not valid.

the code trying execute is:

with objexcelwb.sheets("extraction_breaches")             .range("a2:aw138").sort( _             key1:= .range("a2:a138"), _             order1:=excel.xlsortorder.xlascending, _             type:=excel.xlsorton.xlsortonvalues, _             dataoption1:=excel.xlsortdataoption.xlsortnormal, _             header:=excel.xlyesnoguess.xlno, _             matchcase:=false, _             orientation:=excel.xlsortorientation.xlsortcolumns, _             sortmethod:=excel.xlsortmethod.xlpinyin) end 

i trying

activeworkbook.worksheets("sheet1").sort.sortfields.clear activeworkbook.worksheets("sheet1").sort.sortfields.add key:=range("d1"), _     sorton:=0, order:=2, dataoption:=0 activeworkbook.worksheets("sheet1").sort     .setrange range("a2:s8")     .header = 2     .matchcase = false     .orientation = 1     .sortmethod = 1     .apply end