@domfather
it would be better to post this question over on the Bethesda Game Studios forum where most of the English players are. The reason being is that there are small changes to some quests. I know john moonsugar made a silght changes to that quest to make the dagger a little easier to find but I don't recall where it is right now but he would answer your question quicker over there since he does not frequent this forum and you are playing the English version. Also, if it happens to be a bug he will fix the English version.