testphase resource XML only publishes Title and Description

When using a simple XML resource file (see below) to update the test phase for a given project, the Title and Description fields appear in the GUI after the PUT but the Expected Start and Expected End dates are blank.

<xml>
<testphase>
<dc>Reg</dc>
<dc>Regression</dc>
<alm>Joe</alm>
<qm>2012-12-22T00:00:00</qm>
<qm>2012-12-25T00:00:00</qm>
<testplan>
</testphase>