my datum definition has an error ?

I  reproject  a dwg file  using reproject transformer  from a beijing datum to a WGS84 datum, I used  BURSA  approximations.I'm  sure the  seven  parameters  is correct because  I'v  verified  these in arcmap . I defined  the datum  and the coordinate system  like  below in mycoordsysdefs.fme 

 

 

#DATUM_DEF Beijing1954 \\

 

#   DESC_NM “LocalTranstoWGS84” \\

 

#   SOURCE “me” \\

 

#   ELLIPSOID KRASOV \\

 

#   USE BURSA \\

 

#   DELTA_X -1200.73773931196236 \\

 

#   DELTA_Y 270.135884745262 \\

 

#   DELTA_Z -870.732624966858 \\

 

#   BWSCALE 41.6212793541839  \\

 

#   ROT_X 0.345260849        \\

 

#   ROT_Y 4.031002029         \\

 

#   ROT_Z 0.280361064        

 

 

from the  name list  of  coordinate system gallery  ,I can saw the COORDINATE_SYSTEM_DEF  I defined ,but  the part  info  like this

 

 

ESRI WKT Description

GEOGCS["Unknown",DATUM["D_Unknown",SPHEROID["Unknown",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]]

 

 

1. why the datum and GEOGCS is unknown in esri wkt description ?  I defined them  following the the syntax of definitions  in mycoordsysdefs.fme  .

 

2. the transform result  is out of position about 1 second.  why?

 

can anybody  help me ? thanks in advance.