! Sibling Interaction Model ! CBC data in US twins The following MX script lines were read for group 1 G1: MODEL PARAMETERS CALC NGROUPS=3 BEGIN MATRICES; X LOWER 1 1 FREE ! ADDITIVE GENETIC PATH Y LOWER 1 1 ! SHARED ENVIRONMENT PATH = 0 Z LOWER 1 1 FREE ! NON-SHARED ENVIRONMENTAL PATH B SYMM 2 2 ! SIBLING INTERACTION PARAMETER I IDEN 2 2 H FULL 1 1 END MATRICES; SPECIFY B 0 4 0 MATRIX H .5 BEGIN ALGEBRA; A= X*X' ; C= Y*Y' ; E= Z*Z' ; P= (I-B)~; END ALGEBRA; OPTIONS NO_OUTPUT END The following MX script lines were read for group 2 G2: MALE MZ TWINS IN LARGER FAMILIES DATA NINPUT_VARS=2 NOBSERVATIONS=171 LABELS EXTER1 EXTER2 CMATRIX SYMMETRIC FILE=USCBCMZ.COV We have a problem whose error code is 239 and which I ran across at line number 29 of your input script CMATRIX SYMMETRIC FILE=USCBCMZ.COV ~~~ Yikes!! This file is UNIX format, not DOS format You had better convert it with flip or unx2dos or some such utility. Both are available at the Mx website Problem occurred in group # 2