Does the VBScript_RegExp_55.RegExp object support conditionals?

According to http://www.regular-expressions.info/refflavors.html .NET allows
for conditionals using the (?(if)then|else) structure, and I thought that the
VBScript RegExp object used the .NET flavor of RegEx. But when I try to use
it, the object returns an error message.

When I try to do the following:
objRegExp.Pattern = €œ^(<)?test(?(1)|)$€�
I get the following error message:
Method 'Test' of object 'IRegExp2' failed

I am trying to use RegEx conditionals to ensure that a string with an
opening bracket has a closing bracket. So the RegEx above would accept €œtest€�
or €œ<test€�, but it would not accept €œ<test€� or €œtest€�.

I have looked all over for documentation on the VBScript=RegExp_55.RegExp
flavor of RegEx, but have had little success.

Any help would be greatly appreciated.

Thank you.