I want to call a method from within JS (jQuery to be more specific). This method needs a String parameter and I cant seem to be able to pass this parameter. Here is the relevant bits of code.

The line in bold is how I am calling the apex method. VF code: 

<apex:page controller="DynaTreeHierarchyController" >
<apex:includeScript value="{!URLFOR($Resource.dynatree, '/jquery/jquery.js')}"/>
<apex:includeScript value="{!URLFOR($Resource.dynatree, '/jquery/jquery-ui.custom.js')}"/>
<apex:includeScript value="{!URLFOR($Resource.dynatree, '/jquery/jquery.cookie.js')}"/>
<apex:includeScript value="{!URLFOR($Resource.dynatree, '/src/jquery.dynatree.js')}"/>
<apex:stylesheet value="{!URLFOR($Resource.dynatree, '/src/skin/ui.dynatree.css')}"/>

<script type="text/javascript">

$(function(){
    var dataurl;
    var space = ' ';
    // Variant 1:
    /*$("span.dynatree-edit-icon").live("click", function(e){
        //alert("Edit " + $.ui.dynatree.getNode(e.target));
    });*/
    $("#tree").dynatree({
        onActivate: function(node) {
            $("#info").text("You activated " + node.data.id);
        },
        onRender: function(node, nodeSpan) {
            $(nodeSpan).find('.dynatree-icon')
               .before('<span class="dynatree-icon dynatree-edit-icon"></span>');
        },
        //Variant 2:
        onClick: function(node, f){
            if($(f.target).hasClass("dynatree-edit-icon")){
                $("#info").text("You clicked " + node + ",  url=" + node.data.id);
            }
        },
      children: [
            {title: "Item 1", isFolder: true, id: "http://Item1.com"},
            {title: "Folder 2", isFolder: true, id: "http://Item2.com", 
            children: [
                {title: "Sub-item 2.1", id: "http://sub-item21.com"},
                {title: "Sub-item 2.2", id: "http://sub-item22.com"}
            ]
        },
            {title: "Item 3", id: "http://Item3.com"}
      ],
      dnd: {          
      onDragStart: function(node) {
        $("#info").text("tree.onDragStart " + node.data.id);
        return true;
      },
      onDragStop: function(node) {
        // This function is optional.
        $("#info").text("tree.onDragStop " + node.data.id);
      },
      autoExpandMS: 1000,
      preventVoidMoves: true, // Prevent dropping nodes 'before self', etc.
      onDragEnter: function(node, sourceNode) {
        $("#info").text("tree.onDragEnter " + node.data.id);
        return true;        
      },
      onDragOver: function(node, sourceNode, hitMode) {
        $("#info").text("tree.onDragOver " + node + space + sourceNode + space + hitMode);
        // Prevent dropping a parent below its own child
        if(node.isDescendantOf(sourceNode)){
          return false;
        }
        // Prohibit creating childs in non-folders (only sorting allowed)
        //        if( !node.isFolder && hitMode == "over" )
        //          return "after";
      },
      onDrop: function(node, sourceNode, hitMode, ui, draggable) {
        /** This function MUST be defined to enable dropping of items on
         * the tree.
         */
        $("#info").text("tree.onDrop " + node.data.id + space+ sourceNode + space + hitMode);
        sourceNode.move(node, hitMode);
        myFunc('test this method');
        dataurl = node.data.id;
        // expand the drop target
        //sourceNode.expand(true);
      },
      onDragLeave: function(node, sourceNode) {
        /** Always called if onDragEnter was called.
         */
        $("#info").text("tree.onDragLeave " + node + sourceNode);
      }
    }
    })
});

</script>
<style>

</style>
<div id="tree"></div>
<div id="info"></div>

<!-- 
END JAVASCRIPT, BEGIN APEX CODE
-->
    <apex:form >
        <apex:messages />
        <apex:actionFunction name="myFunc" action="{!IWantToDebug}">
            <apex:param name="param1" value=""/>
        </apex:actionFunction>
    </apex:form>
</apex:page>

The controller code:

public with sharing class DynaTreeHierarchyController {

    public void IWantToDebug() {
        String para = ApexPages.CurrentPage().getParameters().get('param1');
        ApexPages.addmessage(new ApexPages.message(ApexPages.severity.WARNING, 'Msg ' + para));
        System.debug('Called from JS without para ' + para);
    }
}

What am doing incorrectly?