tags error

works tag log:
  ActsAsTaggableOn::Tag Load (2.7ms)  SELECT "tags".* FROM "tags" INNER JOIN "taggings" ON "tags"."id" = "taggings"."tag_id" WHERE "taggings"."taggable_id" = 1127 AND "taggings"."taggable_type" = 'Candidate' AND (taggings.context = 'trades' AND taggings.tagger_id IS NULL)
  ActsAsTaggableOn::Tag Load (1.1ms)  SELECT "tags".* FROM "tags" WHERE (lower(name) = '3ds max')
  ActsAsTaggableOn::Tag Load (2.5ms)  SELECT "tags".* FROM "tags" INNER JOIN "taggings" ON "tags"."id" = "taggings"."tag_id" WHERE "taggings"."taggable_id" = 1127 AND "taggings"."taggable_type" = 'Candidate' AND (taggings.context = 'skills' AND taggings.tagger_id IS NULL)
  ActsAsTaggableOn::Tagging Exists (28.4ms)  SELECT 1 AS one FROM "taggings" WHERE ("taggings"."tag_id" = 311 AND "taggings"."taggable_type" = 'Candidate' AND "taggings"."taggable_id" = 1127 AND "taggings"."context" = 'skills' AND "taggings"."tagger_id" IS NULL AND "taggings"."tagger_type" IS NULL) LIMIT 1


error tag log:
  ActsAsTaggableOn::Tag Load (55.3ms)  SELECT "tags".* FROM "tags" WHERE (lower(name) = 'Łatwość w redagowaniu tekstów pisanych')
  ActsAsTaggableOn::Tag Exists (0.8ms)  SELECT 1 AS one FROM "tags" WHERE "tags"."name" = 'Łatwość w redagowaniu tekstów pisanych' LIMIT 1
  ActsAsTaggableOn::Tag Load (2.2ms)  SELECT "tags".* FROM "tags" INNER JOIN "taggings" ON "tags"."id" = "taggings"."tag_id" WHERE "taggings"."taggable_id" = 1127 AND "taggings"."taggable_type" = 'Candidate' AND (taggings.context = 'skills' AND taggings.tagger_id IS NULL)
  ActsAsTaggableOn::Tagging Exists (0.8ms)  SELECT 1 AS one FROM "taggings" WHERE ("taggings"."tag_id" IS NULL AND "taggings"."taggable_type" = 'Candidate' AND "taggings"."taggable_id" = 1127 AND "taggings"."context" = 'skills' AND "taggings"."tagger_id" IS NULL AND "taggings"."tagger_type" IS NULL) LIMIT 1