With RegularExpressionObject
      .Pattern = "<ClientAvailable\b[^>]*>(.*?)</ClientAvailable>"
    .IgnoreCase = True
    .Global = True
  End With
  Set expressionmatch = RegularExpressionObject.Execute(StringToSearch)


Parsing XML "by hand" using regular expressions is a really bad idea. It might work 99% of the time, but sooner or later you'll discover you aren't doing it correctly according to the XML specification. For example, you aren't handling namespaces properly and you aren't allowing for the fact that whitespace is allowed at certain places within the start and end tags. It's also likely to be much slower than using a proper XML parser.

Raising new questions on an existing thread on a forum is also a bad idea, especially if there are dozens of existing messages - you'll find that many people have lost interest in the thread and therefore aren't available to answer your new question.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference