Namespace in xml element

I have an xml file tagged with namespaces:
for example, ce:section, ce:para

i just trying to collect the 'ce:floats' xml nodes by using the following code:

//Defining the Namespace in the array of arrays of 2 strings
Dim NmSpArr(,) As String = {{"sb", "http://www.elsevier.com/xml/common/struct-bib/dtd"}, {"cl", "http://xml.cengage-learning.com/cendoc-core"}, {"ce", "http://www.elsevier.com/xml/common/dtd"}, {"aid", "http://ns.adobe.com/AdobeInDesign/4.0/"}, {"aid5", "http://ns.adobe.com/AdobeInDesign/5.0/"}, {"xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance"}, {"xmlns:mml", "http://www.w3.org/1998/Math/MathML"}, {"xmlns:xlink", "http://www.w3.org/1999/xlink"}}

//Trying to collect the 'ce:floats'
Dim obj As InDesign.Objects = IndDoc.XMLElements(1).EvaluateXPathExpression("//ce:floats", NmSpArr)

ID CS4
Vb.net

Above code always returning 0 as count. It seems there is problem with the xml namespaces definition.

Any help would be greately appreciated.

Regards,
Suresh