Try mapping it in UVMapper, saving it as a new object and then importing it into Carrara.  Otherwise you need to convert it to a vector object, assign the material zones and use the internal uv mapper to get a reasonable mapping.  Carrara does a fair job but doesn't give you the fine control you get in UVMapper.  I have had this same problem in Carrara and it usually is a messy UV Mapp where the map wraps around to the other side of a flat UV map.  In other words in stead of breaking the map at the edge it connects it to the other edge across the map.  Seems wrong but it does it especially with cylendrical mapping.  If you take one out of  Carrara (export) and look at it in UVMapper you will see what I mean.  Simply mapping it in UVMapper usually fixes this problem.

Dan