This could be caused by the schema definition.
Some schemas have many top level elements defined, including the actual root
e.g.
<element name=\”root\”>
<complextype>
<element ref=\”child1\”>
<element ref=\”child2\”>
<element ref=\”child3\”>
</complextype>
</element>
<element name=\”child1\”/>
<element name=\”child2\”/>
<element name=\”child3\”/>
You may like to open the schema definition and set the Root Reference property on the <schema> node to be OrderIn.