How to use logical And in VoiceXML

I am try to use "logical and" in voicexml(with Viecore extensions)

Here is my code:

<if cond="(menuChangeOn == 'YES')&&(businessGroup == '<%=Viecore.ABCCompany.DataAccess.Constants.CURRENT_MODULE.Main_Number%>')">

The "&&" seems to cause trouble while the voice xml file is parsed.

What's the best practice to resolve this common problem?

It XML, so you must use XML entities & for the ampersand symbol. So instead of &&, use &&.