这是我的log， 里面的“NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.…… 是什么意思？怎么改好？请大虾们帮帮忙：
1024  data car.stkret;
1025  set car.stkret ;
1026  stkr=stkr+0;
1027  run;

NOTE: Character values have been converted to numeric values at the places given by:
      (Line):(Column).
      1026:6
NOTE: Numeric values have been converted to character values at the places given by:
      (Line):(Column).
      1026:10
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503103
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503104
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503105
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503106
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503107
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503108
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503109
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503110
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503111
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503112
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503113
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503114
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503115
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503116
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503117
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503118
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503119
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503120
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503121
NOTE: Invalid numeric data, stkr='Dretnd' , at line 1026 column 6.
ERROR: Limit set by ERRORS= option reached.  Further errors of this type will not be
       printed.
stkcd=Stkcd trddt=Trddt stkret=Dretnd mkttype=Markettype stkr=. _ERROR_=1 _N_=3503122
NOTE: Missing values were generated as a result of performing an operation on missing
      values.
      Each place is given by: (Number of times) at (Line):(Column).
      174 at 1026:10
NOTE: There were 3503276 observations read from the data set CAR.STKRET.
NOTE: The data set CAR.STKRET has 3503276 observations and 5 variables.
NOTE: DATA statement used (Total process time):
      real time           14.04 seconds
      cpu time            13.23 seconds