Halion 6 not launching from Cubase

HI, Has anyone else come across the problem of Halion 6 not appearing as a VST Instrument in Cubase? Hopefully I am being a complete idiot and this is easy to fix/explain. It is a while since I upgraded anything with Steinberg, but it use to be the case of simply making sure you had the dll file for your vst instrument under the vst directory on Cubase. I can’t seem to find anything like a Halion.dll - has the format/name of this type of file changed?

F.y.i. I can launch Halion as a standalone with no problems so far.

Ah - I think I know what my problem is.

Sorry if the answer to this is obvious: Can I run 64 bit Halion 6 VST from within a Cubase Host running under 32 bit?