"Do not fear going forward slowly; fear only to stand still." -- Chinese Proverb
No matter the length of your sales cycle, there's always one customer who will take longer to buy than others. Whether your client is dealing with a number of other priorities, changes at his company or simply likes to proceed with caution, some sales require you to move one step at a time, sometimes taking two steps back to take one step forward.
It's ok to have some of these in your sales funnel, as long as you know they're a good prospect and you put together a plan to continually reach out to them over time. Often times, just sticking around will prove to your prospect that they can trust you with the sale.