XSLT mapping with special tag oa:

I have the source record's element as oa:CityName, How can I map it to my destincaiton element?

I was trying as below but, it saying "Expected end of the expression ',' found ':' "

I knew, what does error message saying, but how to map it by mentioning the oa:CityName value?

Source XML

<?xml version="1.0" encoding="utf-8"?>
<Address>      
  <oa:CityName>Phoenix</oa:CityName>      
</Address>  

Destination XML

<DestinationChildRecord>
  <CityName/>      
</DestinationChildRecord>

XSLT Mapping

<DestinationChildRecord>
  <CityName>
    <xsl:value-of select="ns0:Address/ns0:oa:CityName" />
  </CityName>
</DestinationChildRecord>  

Thanks in Advance.