You can check the format of your datablock.xml file by opening in HydroHub (using just File->Open). Any errors will be reported in the log window.
For HydroHub the order of the elements is important. It should be
<Profile>
<AggregateProfile>
<Curtain>
<Sheet>
<AggregateSheet>
<Outflow>
<General3D>
<All3D>
<Drifter>
Chris