[RESOLVED] Set element value using jQuery, but did not change when post to code behind

[Krokonoster]

I got a asp:label (hidden by css) to which I store something.

I could not use a hiddenfield since you cannot set a css class on it.
I need a css class so I can select it in jQuery.
I cannot select by Id since asp.net webforms change your id.
I cannot use xxxxx.ClientId, since my jQuery script isn't on that form (oh oh, i miss my mvc)

Anyhow, I pop up a dialog, let the user type sth in.
When the dialog closes, I set that label to whatever the use typed in the dialog.
That work (I'm testing for now using some alerts) but when I add a button, and in it's click event check the value of taht label, it is still what it originally have been though. (hmmmm....what I missed?)

Here is the content of my usercontrol (at run time add as many as needed of them to my view):

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="DisputeEntry.ascx.cs" Inherits="TimeSheetDispute.DisputeEntry" %>
<p class="field switch">
    <asp:label runat="server" class="disputeReason" ID="disputeReason"></asp:label>
    <label class="cb-enable selected"><span>Y</span></label>
    <label class="cb-disable"><span>N</span></label>
    <input type="checkbox" id="checkbox" class="checkbox" />
    <asp:TextBox CssClass="workDateId" ID="workDateId" runat="server"></asp:TextBox>
</p>

And in my page, the code that deal with it:

// Brings up a jQuery UI Dialog containing a textarea to which the user can enter a dispute
// Upon close, place that reason in the hidden input we keep for each date.
function GetDisputeReason(parent) {
    var disputeReasonElement = $('.disputeReason', parent);
    var existingDispute = disputeReasonElement.val();
    var win = $('<div><p>Enter your reason for dispute:</p></div>');
    var userInput = $('<textarea style="width:100%">' + existingDispute + '</textarea>');
    userInput.appendTo(win);
    $(win).dialog({
        'modal': true,
        'buttons': {
            'Ok': function () {
                $(this).dialog('close');
                var reason = $(userInput).val();
                alert(disputeReasonElement.val());
                disputeReasonElement.val(reason);
                alert(disputeReasonElement.val());
            },
            'Cancel': function () {
                $(this).dialog('close');
                return '';
            }
        }
    });
}

Those alert's confirm the value of my label have been set.
(dang I just remembered sth about webforms..that value probably sit in the viewstate and my code read that, not the value of my label)

Any ideas?