[Tilesathome] Black tiles in lowzoom

[Rob Reid]

Yesterday I was fixing ocean tiles off the east coast of Australia.
This morning when I checked the area it appears to be showing completely 
black tiles on the lowzoom.
The tiles appear ok at z12 but are black at z6-z11.

See 
http://www.informationfreeway.org/?lat=-19.590428679326394&lon=147.65718544402932&zoom=7&layers=B000F000F 


These are tiles I rendered in xy mode using rev. 10259 and then uploaded.
At least one of the tiles has since been re-rendered by someone else 
using old oceantile settings but most are still showing as being 
uploaded by me (rcr).

My question is how can I tell if it is me uploading duff tiles or the 
lowzoom process having problems.
I have recently done a lot of oceantile fixes and have not seen these 
problems before.

cheers

rcr