XmlRole query number()

XPath expression when using number() function does not return value if number is equal to 0

XML File

<dictionary>
  <case1>0</case1> 
  <case2>0</case2> 
  <case3>1</case3> 
  <case4>1</case4> 
</dictionary>

case1: 0
case2:
case3: 1
case4: 1

I attached demo app