Accounts query error

If i try to return meteor.users aquery like this:
var thumb_Id = Meteor.users.findOne({_id:user_id},{“profile.Thumbnail_URL”:1});
Session.set(‘image_id’, thumb_Id.profile.Thumbnail_URL);
I get the following error:
Exception in callback of async function: TypeError: Cannot read property ‘profile’ of undefined
at null. (http://localhost:3000/app/router.js?27b3440134a4ce7311d05151bf7fe61ef0570289:39:37)
at boundNext (http://localhost:3000/packages/iron_middleware-stack.js?3370bd57ef7b310cca3f5dddb11b77fafdcfc1eb:418:31)
at Meteor.bindEnvironment [as next] (http://localhost:3000/packages/meteor.js?9730f4ff059088b3f7f14c0672d155218a1802d4:999:22)
at null. (http://localhost:3000/app/router.js?27b3440134a4ce7311d05151bf7fe61ef0570289:31:10)
at http://localhost:3000/packages/iron_router.js?c564289eeaa191561eba900052037432ebfcbe4a:1203:36
at _.extend.withValue (http://localhost:3000/packages/meteor.js?9730f4ff059088b3f7f14c0672d155218a1802d4:971:17)
at Router.addHook.hookWithOptions (http://localhost:3000/packages/iron_router.js?c564289eeaa191561eba900052037432ebfcbe4a:1202:27)
at boundNext (http://localhost:3000/packages/iron_middleware-stack.js?3370bd57ef7b310cca3f5dddb11b77fafdcfc1eb:418:31)
at Meteor.bindEnvironment (http://localhost:3000/packages/meteor.js?9730f4ff059088b3f7f14c0672d155218a1802d4:999:22)
at onRerun (http://localhost:3000/packages/iron_router.js?c564289eeaa191561eba900052037432ebfcbe4a:515:9)
spacebars-runtime.js:136 Uncaught Error: Can’t call non-function: undefined