new XForms Binding Exception in X-Smiles

Hello,

Trying the new X-Smiles version I realized that the following code (actually the line conatining the string-length testing), which worked fine in X-Smile 0.7, produces an XForms Binding exception.

<xforms:repeat nodeset="//tm:topicMap/tm:association" id="associationRepeat">
	<xforms:select1 ref="tm:instanceOf/tm:topicRef/@xlink:href" class="associationInstanceOf">
		<xforms:label>Typ of the Association: </xforms:label>
		<xforms:hint>Please choose a name for your association</xforms:hint>
		<xforms:itemset nodeset="//tm:topicMap/tm:topic/tm:baseName/tm:baseNameString[string-length()!=0]">
			<xforms:label ref="." />
			<xforms:value ref="../../@id" />
		</xforms:itemset>
	</xforms:select1>
</xforms:repeat>

Is there a mistake in my code?
Please help me.

wbr,
Roman