500 internal Server error

Hello,
I have this probleme that i cant resolve
when i launch my test with this

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:mas="url" xmlns:env="url" xmlns:env1=url">
   <soapenv:Header/>
   <soapenv:Body>
      <mas:SearchOnlineRegistrations>
         <!--Optional:-->
         <mas:identification>
            <!--Optional:-->
            <env:SystemuserId>35463</env:SystemuserId>
            <!--Optional:-->
            <env:Token>4e29efghtrryererterad3-7b2dghd-4df9-8a4gfhfgh33a</env:Token>
         </mas:identification>
         <!--Optional:-->
         <mas:lsObjects>
            <!--Zero or more repetitions:-->
            <env1:SearchObject>
               <!--Optional:-->
               <env1:PropertyToSearchName>LastName</env1:PropertyToSearchName>
               <!--Optional:-->
               <env1:SearchComparer>Equals</env1:SearchComparer>
               <!--Optional:-->
               <env1:Value>test3</env1:Value>
            </env1:SearchObject>
         </mas:lsObjects>
         <!--Optional:-->
         <mas:pagingObject>
            <!--Optional:-->
            <env1:OrderObjects>
               <!--Zero or more repetitions:-->
               <env1:OrderObject>
                  <!--Optional:-->
                  <env1:SortColumn>ID</env1:SortColumn>
                  <!--Optional:-->
                  <env1:SortOrder>Ascending</env1:SortOrder>
               </env1:OrderObject>
            </env1:OrderObjects>
            <!--Optional:-->
            <env1:PageSize>5</env1:PageSize>
            <!--Optional:-->
            <env1:StartAt>0</env1:StartAt>
         </mas:pagingObject>
      </mas:SearchOnlineRegistrations>
   </soapenv:Body>
</soapenv:Envelope> 

it sends as a result 500 internal server error
and for the assertion SOAP Response:
line -1: error:Unexpected element: TAG_END
line 1: Unexpected element: TAG_END
I am new to soapUI and testing at all and i have been trying all day to figure out whats wrong, could you please help.