Copy to XLS in VFP versions before VFP8 supports only 16000 rows.
If you have more then 16000 rows you can split the file to multiple XLS files with 16000 rows in every.

USE active1
gcDelimName = ALIAS( ) + '.xls'
gcDelimFile = PUTFILE('excel_file:', gcDelimName, 'xls')
IF EMPTY(gcDelimFile)
   RETURN
ENDIF
IF RECCOUNT() < 16001
   COPY TO (gcDelimFile) XLS   && Create delimited file
ELSE
   gcDelimFile = PUTFILE('excel_file:', gcDelimName, 'xls')
   cFilePath = ADDBS(JUSTPATH(gcDelimFile))
   cFileName = JUSTSTEM(gcDelimFile)
   cFileExt  = JUSTEXT(gcDelimFile)
   nFileCnt  = 1
   GO TOP
   DO WHILE .NOT. EOF()
      cTarget = cFilePath+cFileName+"_"+ALLTRIM(STR(nFileCnt))+"."+cFileExt
      nFileCnt= nFileCnt + 1 
      COPY TO (cTarget) NEXT 16000
   ENDDO
ENDIF