Resolution:
For Booleans in BW they are  treated as strings.
XPath treats all values from your data (i.e. from variables) as strings regardless of what the schema says it is.

As see the attached sample in that in order for the Boolean to work correctly you have to cast it as a string in the Transition formula

$Decision=string(true())

A string is converted to a boolean with the following formula:

'string.length()&gt0' not, as you might guess, by 'string="true"'.

Please see for further information
http://www.w3.org/TR/xpath.