Multiple handlers with Prototype.js

[gegaenator]

Hi all,

I've just started scripting with Prototype library. And my question
about Event.observe:
Why the second handler do not work ?

Code:
<script>
Event.observe(document,'load',alertOnLoad, false);
Event.observe('theDiv','mouseover',alertOnMouseOve r,false);

function alertOnLoad() {
alert('alertOnLoad !');
};

function alertOnMouseOver() {
alert('alertOnMouseOver !');
};
</script>
When the pointer's above div block element with theDiv attribute
alert() isn't triggered.The onclick also do not work properly.

Cheers.

[gegaenator]

oh, and here's the log form the JavaScript consle:
(about Prototype.js)

Error: element has no properties
Line: 1502