The @SPTABLERNDV is used to associate random variables with an instance of a discrete outcome table.  The format of @SPTABLERNDV is:

@SPTABLERNDV( 'DIST_INSTANCE_NAME',  RANDOM_VAR_1[, ... , RANDOM_VAR_N]);

When the parent outcome table was defined using @SPTABLESHAPE, the number of associated random variables was also declared.  The number of variables associated with the specified outcome table instance does not match this declared number.  For more information on defining outcome tables and using @SPTABLERNDV, please refer to the Declaring Outcome Tables section of Chapter 14.