Use the latest version of Circos and read Circos best practices—these list recent important changes and identify sources of common problems.
If you are having trouble, post your issue to the Circos Google Group and include all files and detailed error logs. Please do not email me directly unless it is urgent—you are much more likely to receive a timely reply from the group.
Don't know what question to ask? Read Points of View: Visualizing Biological Data by Bang Wong, myself and invited authors from the Points of View series.
The radial position of ticks and labels can be adjusted by the offset parameter.
The tick mark offset can be specified in the <ticks> and/or <tick> blocks. The offset can be in pixels, or specified relatively (in which case it is relative to ideogram thickness) and controls the degree of radial shift applied to both the tick mark and its label (it would not be wise to shift the tick mark without applying the same offset to the label). Both the tick mark and the label are shifted by the same amount (independent offset can be applied to the label - read below).
<ticks> ... offset = 2p ... <tick> offset = 1p ... </tick> </ticks>
The label offset is an additional offset that can be applied to the label, without further disturbing the radial position of the tick mark.
Both global and local label offsets are allowed, and they are cumulative.
A label offset expressed in relative form (label_offset=0.5r) is relative to the size of the corresponding tick.
<ticks> ... # all labels offset by 0.4x their tick size label_offset = 0.4r ... <tick> # this label has an additional 2 pixel offset label_offset = 2p ... </tick> </ticks>