How to update Funding Amount on Associated Project under a Contract Line using SOAP web services

Summary:

I need to update the Funding Amount on a number of Associated Project lines under a Contract Line.

Content (required):

I've used the code below to update the funding amount but I get an error message that makes no sense.

Can someone help please?

<soapenv:Body>

        <typ:mergeContract>

            <typ:contractHeader>

                <con:Id>300000257967373</con:Id>

                <con:MajorVersion>3</con:MajorVersion>

                <con:OrgId>300000046987012</con:OrgId>

                <con:ContractLine>

                    <con:LineNumber>1</con:LineNumber>

                    <con:Id>300000257967375</con:Id>

                    <con:LineId>300000257967376</con:LineId>

                    <con:MajorVersion>3</con:MajorVersion>

                    <con:AssociatedProject>

                        <con:LinkId>300000257967470</con:LinkId>

                        <con:MajorVersion>1</con:MajorVersion>

                        <con:ProjectId>300000243628057</con:ProjectId>

                        <con:ProjectNumber>WTP001</con:ProjectNumber>