AJAX Scroller is generating errors

configuration :
Joomla 1.7.3
Ajax Scroller 2.1.4

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With Chrome, using "web inspector", I see that there are two errors generated by AJAX Scroller at EACH ROTATION !
Please could you help to solve this ?

This seems to be linked to Mootools (see below) but AJAX Scroller is configured with "Include Mootools = NO" ...

Here are the two errors:

1/
Uncaught TypeError: Object function (){e(this);if(g.$prototyping){return this;}this.$caller=null;var i=(this.initialize)?this.initialize.apply(this,arguments):this;this.$caller=this.caller=null;
return i;} has no method 'set'
Class.next
i.extend.$owner  [ mootools-core.js:136 ]
(anonymous function)  [mootools-core.js:84 ]
(anonymous function) [mootools-core.js:80 ]

2/
Uncaught TypeError: Cannot call method 'replace' of null
Class.next
i.extend.$owner  [ mootools-core.js:136 ]
(anonymous function)  [mootools-core.js:84 ]
(anonymous function) [mootools-core.js:80 ]

Does it happen on my demo site? If not, it's a problem on your site and conflict with some other module / plugin.