Command syntax error on EPP DOMAIN CREATE

Trying to execure EPP DOMAIN CREATE through sidn.nl API - HELLO, LOGIN and DOMAIN CHECK work correct, so session is open and server is responding.

Returns "Command syntax error" on this command:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
<command><create>
<domain:create xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
<domain:name>5gmobiel.nl</domain:name><domain:period unit="y">1</domain:period><domain:ns>
<domain:hostObj>ns1.sidn.nl</domain:hostObj></domain:ns>
<domain:ns><domain:hostObj>ns2.sidn.nl</domain:hostObj></domain:ns>
<domain:registrant>FLO015428-AFGLI</domain:registrant>
<domain:contact type="admin">FLO015428-AFGLI</domain:contact>
<domain:contact type="tech">FLO015428-AFGLI</domain:contact>
<domain:authInfo><domain:pw></domain:pw></domain:authInfo>
</domain:create></create>
<extension>
<secDNS:create xmlns:secDNS="urn:ietf:params:xml:ns:secDNS-1.1"></secDNS:create></extension>
<clTRID>AFREG-12345</clTRID>
</command></epp>

Result:

<response><result code="2001"><msg>Command syntax error</msg></result><trID><clTRID>AFREG-12345</clTRID><svTRID>SIDN</svTRID></trID></response>

XML was validated by https://validator.w3.org/check

Solution

That xml works:

 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
    <command>
    <create>
    <domain:create xmlns:domain="urn:ietf:params:xml:ns:domain-1.0">
    <domain:name>testtest.nl</domain:name>
    <domain:period unit="m">12</domain:period>
    <domain:ns>
    <domain:hostObj>ns1.yourdomain.com</domain:hostObj>
            <domain:hostObj>ns2.yourdomain.com</domain:hostObj>
            </domain:ns>
    <domain:registrant>TES093515-X1584</domain:registrant>
    <domain:contact type="admin">TES093515-X1584</domain:contact>
        <domain:contact type="tech">TES093515-X1584</domain:contact>
    <domain:contact type="billing">TES093515-X1584</domain:contact>
    <domain:authInfo>
    <domain:pw>qcbJsi68k-;P04QxVTKsU</domain:pw>
    </domain:authInfo>
    </domain:create>
    </create>
    <clTRID>1477398822-5wsm4XbVrt</clTRID>
    </command>
    </epp>

Dealing with sidn.nl, you should rely only on community as their manuals are outdated, tech support is rude and non-constructive.