xpath with multiple criterias over siblings and position

I have following xml document. I want to extract the value of the Child Data with name='Category' and value='bb' which following-sibling name='WayPointNumber'. I have tried somthing like this:

//Data[[@name='Category' and ./value='bb'] and [/following-sibling::*[(@name='WayPointNumber')]]]/ExtendedData/Data[5]

But i always get an error: ERROR - Failed to evaluate XPath expression: Unexpected token "[" in path expression

How is the correct syntax?

<root>
 <ExtendedData>
      <Data name="Tournumber">
        <value>1</value>
      </Data>
      <Data name="Guide">
        <value>lago di garda</value>
      </Data>
      <Data name="Category">
        <value>Numbering</value>
      </Data>
      <Data name="Category">
        <value>bb</value>
      </Data>
      <Data name="WayPointNumber">
        <value>13</value>
      </Data>
      <Data name="Type">
        <value>POI</value>
      </Data>
      <Data name="Hashlink">
        <value>1_822606</value>
      </Data>
      <Data name="LocalId">
        <value>822606</value>
      </Data>
 </ExtendedData>
 <ExtendedData>
      <Data name="Tournumber">
        <value>1</value>
      </Data>
      <Data name="Guide">
        <value>lago di garda</value>
      </Data>
      <Data name="Category">
        <value>Numbering</value>
      </Data>
      <Data name="WayPointNumber">
        <value>14</value>
      </Data>
      <Data name="Type">
        <value>POI</value>
      </Data>
      <Data name="Hashlink">
        <value>1_822557</value>
      </Data>
      <Data name="LocalId">
        <value>822557</value>
      </Data>
 </ExtendedData>
</root>