function CheckBoxValidatorDisableButton(chkId, mustBeChecked, btnId)
{
var button = document.getElementById(btnId);
var chkbox = document.getElementById(chkId);

if (button && chkbox)
{
button.disabled = (chkbox.checked != mustBeChecked);
}
}

function CheckBoxValidatorEvaluateIsValid(val)
{
var control = document.getElementById(val.controltovalidate);
var mustBeChecked = Boolean(val.mustBeChecked == 'true');

return control.checked == mustBeChecked;
}

function CheckBoxListValidatorEvaluateIsValid(val)
{
var control = document.getElementById(val.controltovalidate);
var minimumNumberOfSelectedCheckBoxes = parseInt(val.minimumNumberOfSelectedCheckBoxes);

var selectedItemCount = 0;
var liIndex = 0;
var currentListItem = document.getElementById(control.id + '_' + liIndex.toString());
while (currentListItem != null)
{
if (currentListItem.checked) selectedItemCount++;
liIndex++;
currentListItem = document.getElementById(control.id + '_' + liIndex.toString());
}

return selectedItemCount >= minimumNumberOfSelectedCheckBoxes;
}