Mongo error on deploy to meteor.com


#1

I am developing on Windows and everything is OK. When I deploy to meteor.com I get a

MongoError: $each term takes only $slice (and optionally $sort) as complements [409]

Error in relations to this method.

setFave: function(recordId, userId){
    Records.update(recordId, { $push: { favouritedBy: userId }});
},

Any ideas?