Hydrax 0.5 HLSL error

Hello,

I have setup a basic hydrax water plane without problem, and all seems working fine. When i added 'Hydrax::HYDRAX_COMPONENT_UNDERWATER' to Hydrax::setComponents(), the program fails with the following error

18:47:49: [Hydrax] Depth material created.
18:47:49: [Hydrax] Creating underwater material...
18:47:49: OGRE EXCEPTION(3:RenderingAPIException): Cannot assemble D3D9 high-level shader _Hydrax_Underwater_Compositor_Shader_VP Errors:
(4): error X3508: 'main_vp': output parameter 'oPosition_' never assigned a value
in D3D9HLSLProgram::loadFromSource at OgreD3D9HLSLProgram.cpp (line 199)
18:47:49: High-level program _Hydrax_Underwater_Compositor_Shader_VP encountered an error during loading and is thus not supported.
OGRE EXCEPTION(3:RenderingAPIException): Cannot assemble D3D9 high-level shader _Hydrax_Underwater_Compositor_Shader_VP Errors:
(4): error X3508: 'main_vp': output parameter 'oPosition_' never assigned a value
in D3D9HLSLProgram::loadFromSource at OgreD3D9HLSLProgram.cpp (line 199)
18:47:49: OGRE EXCEPTION(2:InvalidParametersException): Named constants have not been initialised, perhaps a compile error. in GpuProgramParameters::_findNamedConstantDefinition at OgreGpuProgram.cpp (line 1087)


I'm stuck at it. Does Hydrax needs special materials or something ? To be sure the underwater/godray is supported on my GFX card, i downloaded the precompiled demo on hydrax 0.5 (the island one) and it works as expected. Any help would be very appreciated.

Thanks a lot !