mjdeacha Depending on how you've played the sim, it can take what seems like forever for an elder to die. Just completing the bodybuilder aspiration will nearly double the elder life stage so it looks like the bar doesn't move unless you pay attention to the actual number. There are other little things that can have an effect on how long a sim lives too. Spellcaster potions for example. Have you used the immortality potion on any sims. That usually only works for elders if I remember correctly. It's been a long time since I've used one.
But, if your elders have stopped aging altogether, do you have any mods that affect aging? Have you set a flag with MCCC for instance? You can also check to see if a sim is truly immortal and how many days are in the sim's life span with SimsInfo (originally by Itasan, now maintained by Frankk). MCCC can give you the info too, but I find SimsInfo easier.
Hope this helps.