many to many - Sequelize belongsToMany -

i have used sequelize , setup many-to-many relationship using belongstomany(). however, when query out data, this:

api.models.operator.find({        where: { id: connection.params.id },        include: [          { model: api.models.permission,            include: [             { model: api.models.activity }           ]         }        ]     }) 

i activity not associated permission! error. why? doesn't fact belongstomany connects activity through permission operator imply association?

my permission model:

module.exports = function(sequelize, datatypes) {    return sequelize.define("permission",      {       id: {         type: datatypes.bigint,         allownull: false,         primarykey: true,         autoincrement: true       },       operator_id: {         type: datatypes.bigint,         allownull: false,         references: 'operator',         referenceskey: 'id',         comment: "the operator in permission."       },       activity_id: {         type: datatypes.bigint,         allownull: false,         references: 'activity',         referenceskey: 'id',         comment: "the activity in permission."       },       createdat: {         type: datatypes.date,         allownull: false,         defaultvalue: datatypes.now,         comment: "date of record creation."       },       updatedat: {         type: datatypes.date,         allownull: false,         defaultvalue: datatypes.now,         comment: "date of last record update."       },       deletedat: {         type: datatypes.date,         comment: "date record marked deleted."       }     },      {       comment: "a permission indicates allowed activity operator, ex: superadmin allowed 'post /workorders'.",       classmethods: {         associate: function(models) {            models.operator.belongstomany(models.activity, {through: models.permission, foreignkey: 'operator_id', ondelete: 'cascade', onupdate: 'cascade'});           models.activity.belongstomany(models.operator, {through: models.permission, foreignkey: 'activity_id', ondelete: 'cascade', onupdate: 'cascade'});          }       }     }   );  } 

which myself resolved follows:

modela.belongstomany(modelb, {         through: 'modelc',         foreignkey: 'modelaid'     }); 

you call:

modela.findall({ include: [{     model: modelb }]}).then(function(success) {}, function(error) {}); 

if want using:

modelb.findall({ include: [{     model: modela }]}).then(function(success) {}, function(error) {}); 

you must declared

modelb.belongstomany(modela, {         through: 'modelc',         foreignkey: 'modelbid'     }); 

^^ luck u!!!! ^^.