Assign Properties editor allows copy operation that validator complains about

The Assign Properties editor allow the following XML to be created:

<bpel:assign validate="no" name="AssignDataForBuyFailed">
<bpel:copy>
<bpel:from>
<bpel:literal xml:space="preserve"><tns:BuyFailed xmlns:tns="http://www.example.org/Store/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<fault></fault>
</tns:BuyFailed>
</bpel:literal>
</bpel:from>
<bpel:to variable="buyFailedVar" part="parameters"></bpel:to>
</bpel:copy>
<bpel:copy>
<bpel:from part="parameters" variable="creditCheckInvalidVar">
<bpel:query queryLanguage="urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0">
<![CDATA[fault]]>
</bpel:query>
</bpel:from>
<bpel:to part="parameters" variable="buyFailedVar">
<bpel:query queryLanguage="urn:oasis:names:tc:wsbpel:2.0:sublang:xpath1.0">
<![CDATA[fault]]>
</bpel:query>
</bpel:to>
</bpel:copy>
</bpel:assign>

See attached screen shot for what this looks like in the property editor. However this generates the following error message:

Description Resource Path Location Type
The LocationPath expression "child::fault" is not allowed in expressions as there is no implicit context node present. PurchaseGoodsProcess_Store.bpel /StoreProcess/bpel line 86 BPEL Validation Marker