It doesnt find nor replaces the strings.. may be wrong regex?

// ==UserScript==
// @name           CurConvertor
// @namespace      CurConvertor
// @description    noam smadja
// @include        http://www.zavvi.com/*
// ==/UserScript==
textNodes = document.evaluate(
                              "//text()",
                              document,
                              null,
                              XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
                              null);
var searchRE = new RegExp('\d\d.\d\d','gi');
var replace = searchRE*5.67;
for (var i=0;i<textNodes.snapshotLength;i++) {
    var node = textNodes.snapshotItem(i);
    node.data = node.data.replace(searchRE, replace);

i wrote this, but its not doing a think. even when i change the string in the regex to a string in the webpage it still does nothing..

what am i missing? :)