The most likely candidate is price. There is always some price that will attract buyers. If you are the lowest price in your area for what you are offering then you will most likely be the first to receive offers. When you have many poepl looking but no offers it means real buyers are deciding to go elsewhere. If your price is significantly off what the market will support you will be attracting the wrong buyers who are expecting more for their money and you will not be attracting buyers who can actually afford your house. Buyers and agents will usually search for properties within a range. If I can afford homes from $500,000-$600,000, I may not be looking at homes over $650,000 for example. If you are priced there but the real market value is in my range I may never consider your home because it is out of my range.
There can be other factors that can be an issue as well. Some properties have one issue that buyers cannot get past in a competitive market. For example if you are on a very busy road, you may appear priced well but buyers simply go to other homes that are similar but are n a quieter street. In that case, the price is still the issue because you cannot change your street and you need to make your house a better deal.
Sometimes there are things that can be done with how a home shows that can help. Talk to your agent about what comments they are getting. What is it that buyers are saying about your home?. Maybe it can show better.
Find out what has been selling that is similar to yours. If they are all priced better then the answer will be obvious