I made a key lime pie with a lemon pie recipe. The recipe was made with cornstarch and egg yolks as opposed to the condensed milk recipes. It did not set up. Do the limes affect the recipe differently than lemon juice does?
There's several things that could have caused this. The lime juice should have worked just like the lemon. Did you follow the recipe exactly? And cook it for the required length of time to let the cornstarch do its job?
One thing that causes corn-starch based sauces to stay thin is if you use a spoon to taste the sauce and then put the spoon back into the sauce. She states that the tiniest amount of your saliva will "digest" the cornstarch enough to keep it from thickening.
I haven't checked this out, but I don't doubt it. On occasion a recipe has failed to "jell" and I just made a slurry of more water and cornstarch, and added a little at a time while stirring over the heat until it looked right.
By the way, if it's not made with condensed milk, it's just a lime pie. No matter what the variation, that's the only way a "key lime pie" is made. Read Bev Avery's take on it: Key Lime Pie - the Final Word! http://sneakykitchen.com/Ideas/key_lime.htm