SuiteTalk SOAP Services

So I'm trying to use PHP to search customer records with a specific value for a custom field. All the examples that I have found do not work. For example this one errors on <serachRecord line with messag "The prefix &quot;xsi&quot; for attribute &quot;xsi:type&quot; associated with an element type &quot;searchRecord&quot; is not bound."

  <soap-env:Body>

        <search xmlns="urn:messages_2020_1.platform.webservices.netsuite.com">

             <searchRecord xsi:type="q1:ContactSearch" 

xmlns:q1="urn:relationships_2020_1.lists.webservices.netsuite.com">

                <ns4:basic xsi:type="ns5:ContactSearchBasic" 

xmlns:ns5="urn:common_2020_1.platform.webservices.netsuite.com">

                    <ns5:email operator="is" xsi:type="ns6:SearchStringField"