my chain is skipping on my single speed
Your chain skipping/dropping could be the result of a few things, so I'll lay them out briefly:


Your chain/freewheel could be worn out. If you recently replaced your chain, the worn out teeth of the freewheel won't mesh with the new chain and will cause skipping. Simply examining the profile of the freewheel teeth with pictures of a new one will give you a sense of whether this is a possibility. (Worn out teeth are sharper at the tops and, in serious wear, form little waves or shark-fins.) 
It is possible that the chain installed is too narrow for the freewheel teeth (though it would be a very noticeable problem.) Muti-speed chains are typically 3/32" wide, while some single speed chains are 1/8" wide. Freewheels are manufactured in both widths. Where one can run a 1/8" chain on either width freewheel, a 3/32" chain will bind noticeably on a 1/8" freewheel.
The singulator installed on your bike may not be providing enough chain tension. The actual alignment of this component won't cause the chain to skip as it it on the slack side of the chain. This is an unlikely scenario but could occur if it has been in service for a while or damaged in some way. Replacing the spring will bring it back to original tension specs.
The most likely thing I can imagine is that your chain-line is off. Your chainring is set further out from the center-line of the bicycle than the freewheel is, causing it to catch on the freewheel teeth and be thrown off. If the bicycle is a homebrewed single-speed, chances are you reused the original crank and bottom bracket spindle that were designed for a multi-speed bike. If this is a store-bought bike, it wasn't set up properly. Here is Sheldon Brown's article explaining the chain-line and how it is adjusted. In a nutshell, you will use different BB spindle lengths, BB spacers, and/or chainring spacers to line up the chainring with the freewheel. This can be done easily if you have the right tools and some patience. Here is a SE question relating to adjusting chainlines. Good luck!