C # arcengine Print out an error in GP call error

 Public Static BOOLSample (list<string>Inrasters,stringLocationdata,stringOuttable,stringResamplingtype,stringoutexcel) {geoprocessor GP=Newgeoprocessor (); Gp. Overwriteoutput=true; stringISTR = inrasters[0];  for(intj =1; J < Inrasters.count (); J + +) {ISTR+=";"+Inrasters[j]; } ESRI. ArcGIS.SpatialAnalystTools.Sample Sam=NewESRI.            ArcGIS.SpatialAnalystTools.Sample (); Sam.in_rasters= ISTR;//inrasters;Sam.in_location_data =Locationdata; Sam.out_table=outtable; Sam.resampling_type=Resamplingtype; Try{GP. Execute (Sam,NULL); }            Catch(COMException e) {stringstr ="";  for(inti =0; I < GP. Messagecount; i++) {str+=GP.                GetMessage (i);                } MessageBox.Show (str); return false; }            if(!excelutil.createexcelbyitable (Outtable,outexcel)) {MessageBox.Show ("failed to build Excel table! "); return false; }                       return true; }

C # arcengine Print out an error in GP call error