Name the Failure (brazing)

I thought my brazing was pretty dialed until I saw this failure. Paint failed first so I sanded the paint away to find this hairline fracture. It's in what I would consider an odd spot, top side of the DT/HT junction. All other brazing on the bike looks solid. First failure I've seen like this.

So, Any ideas what's going on here? (Also, I have no idea how to turn the pic)

Attachment 111645



Cheers,
Matt Manuel

Poor fit-up or lack of capillary penetration into the joint by filler or a combination of both - don't shoot the messenger!

- Garro.

I concur with Garro as per usual.