PROC MI MONOTONE and FCS difference

[chillywind]

I used the regression method. Based on the sas user guild, if the data is monotone, the two statement should get the same result. But I can never get the same result even in the simplest case.

data monotone;
input id a b;
datalines;
1 1 2
2 1 2
3 1 3
4 1 .
5 2 3
;

PROC mi data=monotone out=mi_1 nimpute=1 seed=75319 ;
  class a;
monotone reg(b /details );
VAR a b;
run;

PROC mi data=monotone out=mi_0 nimpute=1 seed=75319 ;
class a;
fcs nbiter=0 reg( b );
VAR a b;
run;