Using a germanium detector array, Hyperball, we have measured gamma rays from several Lambda hypernuclei. In the previous experiments, spin-dependence of LambdaN effective interaction was investigated. In the latest experiment, we have studied B-11(Lambda) in which six gamma transitions have been observed. The result of this experiment suggests that the level structure is quite different from a theoretical prediction based on the LambdaN spin-dependent effective interaction parameters determined in the previous experiments.