Mplus做有调节的中介模型分析

输入的命令如下，但是运行结果一直显示   Unknown function: A1
希望大神给予解答！！

DATA: FILE = workengagement.csv;
VARIABLE: NAMES =sex marriage level bianzhi gangwei x1-x9 M y1-y9 z1-z3;
usevar= x1-x9 M y1-y9 z1-z3 MZ;
DEFINE:MZ=M*z3;
ANALYSIS:
TYPE=RANDOM;
ALGORITHM=INTEGRATION;
ESTIMATOR=ML;
BOOTSTRAP=5000;
MODEL:
X BY x1-x9;
Y BY y1-y9;
Z BY z1-z3;
M ON X(a1);
Y ON
X(c1)
M(b1)
Z
MZ(b2);
[Z](zmean);
Z(varz);
X5 WITH X7;
X8 WITH X9;
Y1 WITH Y2;
Y5 WITH Y6;
Y8 WITH Y9;
MODEL CONSTRAINT:
NEW(indirect lowZ lowmme);
indirect=a1*b2;
lowZ=zmean-sqrt(varz);
lowmme=a1(b1+b2*lowz);
OUTPUT:
CINTERVAL(BCBOOTSTRAP);