lr_xml_set_values (The prefix 'm0' has not been mapped to any URI)

I have come across a situation where i am trying to set values (lr_xml_set_values) in the xml. In xml i see tags as 

<m0:address1>691 KNOX ROAD 100 E</m0:address1>
<m0:city>Abingdon</m0:city>
<m0:countyName/>
<m0:state>IL</m0:state><m0:zipCode>61410</m0:zipCode>

Code:
lr_xml_set_values("XML={XMLrequest}","ResultParam= XMLrequest",
"Query=//m0:address1",
"ValueParam=Address1", LAST);
Returning error is : The prefix 'm0' has not been mapped to any URI

I tried to subout the colon ":" but still it throws the same error.

lr_xml_set_values("XML={XMLrequest}","ResultParam= XMLrequest",
"Query=//m0\:address1",
"ValueParam=Address1", LAST);

I appreciate any suggestions/workarounds?