When you set your price, try that : "would I buy it for this price ??"
Sometimes things don't sell because the price is to high for what it's worth... For example, some item doesn't sell at all when they're above 15k and sells really fast when they're 10k.
If an item doesn't sell for a week : the price is too high or there is really not enough demand compared to the offer (both are more or less linked).