As 'Evil Zymurgist' says more details would help here, but... if you are brewing with pure Molasses then you will be lacking many nutrients required for a healthy/rapid fermentation. Acids such as citric, also you are likely lacking enough nitrogen/amino acids for a vigorous fermentation.
For acid you could add lemon or orange juice, regarding adding nitrogen to the mix you could boil up some raisins or apples and add the pulp to the mix. It will probably ferment to completion without these, but will be far happier with.
Couple of pounds of Molasses, 1 mashed up apple or hand full of raisins, juice of an orange, made up to a gallon should ferment fine. Not sure how it will taste, but fermentation wise it should be OK.
This reminds me of making a mead, but with Molasses rather than honey.