Welcome, Mohammed. I think most experienced MF investors would tell you that you might be biting off more than you can chew for your first deal. It also may be why you're getting the cold shoulder when you approach brokers (more on that later).
Have you ever considered starting w/ 2-4 plexes and scaling from there? The entry point is much easier; you can avoid the commercial brokers for now; you will gain valuable experience on purchasing, making improvements, tenanting and landlording, in an environment where if you do make a mistake, it is not as costly as it would be in a 15-20 unit.
If you had any previous REI experience, I wouldn't be as concerned, but you're kind of going from 0 to 100 pretty quickly here. If you're hell bent on doing this, though, then you're going to need to work on your approach w/ the commercial brokers, or find your deals other ways, such as REIA meetings, referrals (have you asked your contractor & PM if any of their clients wish to sell), driving for dollars, etc.
When you approach a broker, what are you saying? Maybe some of the brokers here can help you sharpen your presentation. For example, above you don't mention the asset Class, unit mix, price range/price per door, general area, or cap you are looking for. If you approach a broker with all that clearly defined, you may find more success.
I hope you don't think I'm being too hard on you. Just giving you some different angles to explore.