How do you filter an XML - with the following query?

Not really sure how to put it, but I can not seem to filter when I used the following clause:  

and c:SampleNumber not like 'NPR%'

Any ideas? What am I doing wrong? Any pointers in the right direction? 

This is the whole code : 

parserName = "xmlHandler"
processXML = samplesXMLResponse

status = XMLParse(parserName, processXML)

' qry = "select c:Programme,c:OrganisationId, c:OrganisationName, c:SampleId, c:SampleNumber, c:MatrixGroup  " 'c:MatrixGroup differentiates between NMD and STEC samples
' qry = qry & "from c:SampleHeader "
' qry = qry & "where c:SampleState = 'Active' " 
' qry = qry & "and c:Programme like 'NMD%'" 

qry = "select c:Programme,c:OrganisationId, c:OrganisationName, c:SampleId, c:SampleNumber, c:MatrixGroup  " 'c:MatrixGroup differentiates between NMD and STEC samples
qry = qry & "from c:SampleHeader "
qry = qry & "where c:SampleState = 'Active' " 
qry = qry & "and c:Programme like 'NMD%' and c:SampleNumber not like 'NPR%' " 


status = ClearArray("sampleIdArray")
status = XMLQuery(parserName, qry, "sampleIdArray")