Index: DamEngine/trunk/xsd/DamOutput.xsd
===================================================================
diff -u -r1567 -r1578
--- DamEngine/trunk/xsd/DamOutput.xsd	(.../DamOutput.xsd)	(revision 1567)
+++ DamEngine/trunk/xsd/DamOutput.xsd	(.../DamOutput.xsd)	(revision 1578)
@@ -11,7 +11,7 @@
           <xs:sequence>
             <xs:element name="CalculationResults" type="CalculationResults" />
             <xs:element minOccurs="0" maxOccurs="unbounded" name="CalculationMessages" type="Message" />
-            <xs:element minOccurs="1" maxOccurs="1" name="OperationalOutputTimeSeries">
+            <xs:element minOccurs="0" maxOccurs="1" name="OperationalOutputTimeSeries" nillable="true">
               <xs:complexType>
                 <xs:sequence>
                   <xs:element minOccurs="0" maxOccurs="unbounded" name="TimeSerie" type="TimeSerie" />