Warning: Input connection incorrectly entered

 warning message: 
in 1:read.table(file=file, header=header, sep=sep, quote=quote, and so on: 
   Input connection 'C:/rdata/cv.csv' has incorrect input 
in 2:read.table(file=file, header=header, sep=sep, quote=quote, and so on: 
  line1appears to contain embedded nulls
3: in read.table(file=file, header=header, sep=sep, quote=quote, and so on: 
  incomplete final line found by readTableHeader on 'C:/rdata/a.xlsx'