LDStructure was a big help in this case:
0 ~Magnet Cylindrical Casing
0 Name: 4106.dat
0 Author: [PTadmin]
0 !LDRAW_ORG Part Alias UPDATE 2012-03
0 !LICENSE Redistributable under CCAL version 2.0 : see CAreadme.txt
0 BFC CERTIFY CW
0 !HISTORY 2011-12-29 [PTadmin] Official Update 2011-02
0 !HISTORY 2012-08-11 [Steffen] Add ~ to title
0 !HISTORY 2012-12-28 [PTadmin] Official Update 2012-03
0 // Alias of 2959
I assume that you did not have the alias files installed. That is also the reason for not showing the parts in the traffic-light4.mpd.
0 ~Magnet Cylindrical Casing
0 Name: 4106.dat
0 Author: [PTadmin]
0 !LDRAW_ORG Part Alias UPDATE 2012-03
0 !LICENSE Redistributable under CCAL version 2.0 : see CAreadme.txt
0 BFC CERTIFY CW
0 !HISTORY 2011-12-29 [PTadmin] Official Update 2011-02
0 !HISTORY 2012-08-11 [Steffen] Add ~ to title
0 !HISTORY 2012-12-28 [PTadmin] Official Update 2012-03
0 // Alias of 2959
I assume that you did not have the alias files installed. That is also the reason for not showing the parts in the traffic-light4.mpd.