I'm having some trouble with isSelector in TimelineMax.min.js and lazyTweens in TimelineMax.js . . . . The project I'm referencing can be accessed with password ' Olympus003 ' at https://st-fresh.github.io/electroncycle/electroncycle.html . . . . . . The _internals object has the isSelector prop on it, and here's the call stack: TimelineMax.min.js:12 Uncaught TypeError: Cannot read property 'isSelector' of undefined at Function.<anonymous> (TimelineMax.min.js:12) at h.check (TweenMax.min.js:15) at new h (TweenMax.min.js:15) at y._gsDefine (TweenMax.min.js:15) at TimelineMax.min.js:12 at TimelineMax.min.js:12 ... ... I noticed that in Timelinemax.js (unminified) the error is a bit different and is with reference to the lazyTweens prop: TimelineMax.min.js:29 Uncaught TypeError: Cannot read property 'lazyTweens' of undefined at Function.<anonymous> (TimelineMax.min.js:29) at h.check (TweenMax.min.js:15) at new h (TweenMax.min.js:15) at y._gsDefine (TweenMax.min.js:15) at TimelineMax.min.js:17 at TimelineMax.min.js:1281 . . . . . . I'm a bit unfamiliar with the TimelineMax library at this time, and just wanted some scope on handling this error, I appreciate any help you can offer within a return message, and thanks for TimelineMax ! What I tried// In the unminified I tried adding TweenLite.js to the project to see if the var dependent on TweenLite would get defined.. This wasn't a quick solution.