can not draw pie with label contained inside canvas

[FLA Admin]

it gives this error for my 12/18-12/14 chart, but i can draw it with 12/11-12/17 chart, and 12/1-12/31 monthly chart. i know what i am grouping with (a custom field) is long, but with the same 3 labels i can do it for some charts, but not the another, which is strange to me. thanks. ting si