I made Istikhaarah for several days regarding a marriage proposal, but I did not get any clear sign in a dream.

Answer

Generally there is no clarity in our dreams due to the deluge of evil in our hearts and brains. There is evil all around us – television, video, haraam facebook, not exercising proper purdah, gheebat, etc., etc. Sin and futility block the spiritual channels, hence the dreams are unclear and no real direction is acquired from Istikhaarah. Recite Istighfaar in abundance and make dua so that the right decision is made.