Error from web service: Incoming data cannot be null. Please validate the input XML data with the schema

[Bob Alston]

Could someone who is skilled in SOAP/XML coding compare my SOAP/XML -
top of listing with the WSDL example version at the bottom. I can
see
differences in the libraries referenced and including the parameter
type info with the parameters. Can't tell of one of these or
something else is the problem.
Clearly I am communicating with my desired web service.
thanks
bob
----My soap message (from Pocket soap) ----
<E:Envelope
xmlns:a="http://www.dshs.state.tx.us/cmbhs/"
xmlns:XS="http://www.w3.org/2001/XMLSchema"
xmlns:XI="http://www.w3.org/2001/XMLSchema-instance"
xmlns:E="http://www.w3.org/2003/05/soap-envelope">
<E:Header>
<a:CMBHSAuthenticationHeader><
CMBHSUserName XI:type="XS:string">xyz</CMBHSUserName>
<CMBHSPassword XI:type="XS:string">xyz</CMBHSPassword>
</a:CMBHSAuthenticationHeader>
</E:Header>
<E:Body>
<a:DownloadDocument>
<parameter>
<ParentOrganizationNbr XI:type="XS:int">1736</ParentOrganizationNbr>
<OrganizationNbr XI:type="XS:int">1736</OrganizationNbr>
<FromDate XI:type="XS:dateTime">2011-04-18T00:00:00Z</FromDate>
<ToDate XI:type="XS:dateTime">2011-04-19T00:00:00Z</ToDate>
<DownloadType XI:type="XS:short">10</DownloadType>
<DownloadDateType XI:type="XS:short">2</DownloadDateType>
</parameter></a:DownloadDocument>
</E:Body>
</E:Envelope>
***************************************************************************
*********
--- from WSDL ---
<soap12:Envelope
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
<soap12:Header>
<CMBHSAuthenticationHeader xmlns="http://www.dshs.state.tx.us/
cmbhs/">
<CMBHSUserName>string</CMBHSUserName>
<CMBHSPassword>string</CMBHSPassword>
</CMBHSAuthenticationHeader>
</soap12:Header>
<soap12:Body>
<DownloadDocument xmlns="http://www.dshs.state.tx.us/cmbhs/">
<Parameter>
<ParentOrganizationNbr>int</ParentOrganizationNbr>
<OrganizationNbr>int</OrganizationNbr>
<FromDate>dateTime</FromDate>
<ToDate>dateTime</ToDate>
<DownloadType>short</DownloadType>
<DownloadDateType>short</DownloadDateType>
</Parameter>
</DownloadDocument>
</soap12:Body>
</soap12:Envelope>