求助各位大神！
做调节效应，用mplus，跑出了的结果显示

*** ERROR
  One or more variables have a variance of zero.
  Check your data and format statement.


哪里出问题了？感谢！！！


附上程序：
title: 第一阶段调节效应的检验;

  data: file is E:\4mpus\11.dat;

  variable: names are id k1-k5 x m y w1 w2 xm mm w1m;

  usevariables are k1-k5 x m w1 int;

  define: int = (x - xm) * (w1 - w1m);

  analysis: bootstrap = 1000;

  model:

  m on k1-k5

  x

  w1

  int;

  output: standardized cinterval(bcbootstrap);