On the development site, the xslt macro seems to work fine, but on the live site, I get these errors :

umbracoMacro InnerException
An error occurred during a call to extension function 'getAllTags'. See InnerException for a complete description of the error.
An error occurred during a call to extension function 'getAllTags'. See InnerException for a complete description of the error.
   at System.Xml.Xsl.Runtime.XmlExtensionFunction.Invoke(Object extObj, Object[] args)
   at System.Xml.Xsl.Runtime.XmlQueryContext.InvokeXsltLateBoundFunction(String name, String namespaceUri, IList`1[] args)

   at System.Xml.Xsl.CompiledQuery.Query.<xsl:template 
match="/">(XmlQueryRuntime 
{urn:schemas-microsoft-com:xslt-debug}runtime, XPathNavigator 
{urn:schemas-microsoft-com:xslt-debug}current, Double 
{urn:schemas-microsoft-com:xslt-debug}position, Double 
{urn:schemas-microsoft-com:xslt-debug}last, IList`1 
{urn:schemas-microsoft-com:xslt-debug}namespaces) in 
D:\Inetpub\foursquare.co.nz\xslt\MainColumn\productPromotionList.xslt:line
 65
   at 
System.Xml.Xsl.CompiledQuery.Query.<xsl:apply-templates>(XmlQueryRuntime
 {urn:schemas-microsoft-com:xslt-debug}runtime, XPathNavigator , Double ,
 Double )
   at System.Xml.Xsl.CompiledQuery.Query.Root(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime)
   at System.Xml.Xsl.CompiledQuery.Query.Execute(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime)

   at System.Xml.Xsl.XmlILCommand.Execute(Object defaultDocument, 
XmlResolver dataSources, XsltArgumentList argumentList, XmlWriter 
writer)
   at System.Xml.Xsl.XslCompiledTransform.Transform(IXPathNavigable input, XsltArgumentList arguments, TextWriter results)
   at umbraco.macro.GetXsltTransformResult(XmlDocument macroXML, XslCompiledTransform xslt, Dictionary`2 parameters)
   at umbraco.macro.loadMacroXSLT(macro macro, MacroModel model, Hashtable pageElements)

umbracoMacro InnerException
An error occurred while parsing EntityName. Line 271, position 63.
An error occurred while parsing EntityName. Line 271, position 63.
   at System.Xml.XmlTextReaderImpl.Throw(String res, String arg)
   at System.Xml.XmlTextReaderImpl.ParseEntityName()
   at System.Xml.XmlTextReaderImpl.ParseEntityReference()
   at System.Xml.XmlTextReaderImpl.Read()
   at System.Xml.XmlLoader.LoadNode(Boolean skipOverWhitespace)
   at System.Xml.XmlLoader.LoadDocSequence(XmlDocument parentDoc)
   at System.Xml.XmlDocument.Load(XmlReader reader)
   at System.Xml.XmlDocument.LoadXml(String xml)
   at umbraco.editorControls.tags.library.getAllTags()