For the sale to appear on the form 4797 as it should, make sure you entered a disposition date sold and sales price.  That should be enough to at least make it show up.  But the most common reason it may still not work is when you are doing a bulk sale, you have to enter the disposition info in the lowest number asset (and the bulk sale info is blank in that one).  Then in the higher number assets that are part of the bulk sale, you must also enter the "Date Sold" (presumably the same date as the main asset). 

That confusing requirement that the lowest number asset has to be the primary one in a bulk sale is a frustrating issue that frequently causes confusion.