The Arc property should be calculated as follows: 2 * Math.PI * SkillsPerOrbitIndex / SkillsPerOrbit[OrbitRadiiIndex] instead of 2 * Math.PI * SkillsPerOrbitIndex / SkillsPerOrbit[SkillsPerOrbitIndex]. The latter throws an index out of bounds exception due to SkillsPerOrbitIndex being greater than 4 in some cases.