虚拟变量都要加i.

  For interactplot to properly work, the package catplot has to be installed.  This can be done  with ssc install catplot.  interactplot does not work properly if you use prefixes other than i.    or c., i.e. the capitalized variants I. or C., and other coding-related prefixes.  The program    can handle simple time-series operators (l., L., d., D., L1., L2., etc.), however, more complex    constructs (e.g. DL(1/4).xvar) can lead to erroneous output.  In such cases it is therefore    necessary to generate the lagged or differenced instances of the variables beforehand and run    the regression model with the newly generated variables in a second step before executing    interactplot.