[Tilesathome] lowoom Caption Layer question

[Brent Easton]

>The instructions say:
>
>Make sure that the caption layer has been uploaded and that the tiles are
>downloadable
>
>What is the easiest way to check this?

Ok, I worked this out and got most things working, however I seem to have a problem with blank caption tiles:-

Any tile, at any zoom (8-11) that does not have any part of a caption on it, ends up as a blank tile after the lowzoom_composite layers the caption over the captionless tile. I have checked that the caption layer is correct and the captionless tiles look correct also.

You can see the effect on the level 8 tile 227 153. Zoom in to level 10 and all tiles not near the captions are blank.

I am on Xp with Activestate Perl v5.8.8 and Image Magick v6.3.5.

Thanks,
Brent.