SOAP-ENV:MustUnderstand

Hello,
I write soap server using php5, SoapServer class etc. It should support
delphi client already written by someone else. I have an error:
<faultcode>SOAP-ENV:MustUnderstand</faultcode>
<faultstring>Header not understood</faultstring>

I've used netcat and program sends something like that:
<SOAP-ENV:Header>
<ns2:TSecurity xsi:type="ns2:TSecurity" SOAP-ENV:mustUnderstand="1">
<UserName></UserName>
<Password></Password>
<TID>{001,MON,DVL,203,556083}</TID>
</ns2:TSecurity>
</SOAP-ENV:Header>

If I set mustUnderstand="0" and telnet on 80 port with all data it
works great :/
What should I do receive that header on my server without any problems?

Greetings,
r.