Young rats wont eat rat food

Question
I have two albino pink-eyed rats, both of them young. I'm not really sure about their exact age, but I'm guessing one is going on two months and one is a month to a month and a half. They may be older, I bought them from a pet store that had their two pairs of adult mice each have a litter probably a month before. I've been searching for the right food to give them. I tried Kaytee Forti-Diet Pro Health which says it is meant for rats. At first I only had the older one and he ate that fine. I also gave him some food from Kaytee Fiesta Mix which is more for hamsters and gerbils but he seemed to like some of the stuff in there. Along with that I gave him broccoli and he loved that. After I got the second one to keep him company, though, they both stopped eating the forti-diet within a couple of days. But they would still eat everything else that they had eaten before. I bought Oxbow Regal Rat food seeing that it was especially formulated for rats and they ate that for a couple days but then stopped as well. They eat everything else as before but I know that they can't survive purely on that. I've also given them dry cat food a couple of times and they loved that. I'm not really sure what I should do so they do eat properly. Please help.

Answer
Store-bought diets are nothing but junk. They have a lot of foods that rats either can't eat (for 'filler'), shouldn't eat (due to it being pretty unhealthy for them) or won't eat (due to taste preferences). Since these guys are picky, I'D suggest making your own diet. In a lot of ways it can be done quickly and very cheaply.

Go to google and look up "Suebee's Rat Diet" for a guideline -- remember that you can tweak it and use as many knock off items as you want, just keep your sugars and fats low and remember to give them a "staple" as well, like a lab block. If you want to go cheap on the lab block, I suggest using Mazuri blocks, they can be found at PetSmart or Petco. I personally mix my own rat food and I change it from week to week as I add to it. Right now, my mix is something like as follows:

whole grain cheerios
popcorn (plain, popped)
dried vegetable rigatoni (you can use whole wheat pasta as well)
dehydrated/dried vegetables (variety mix)
dehydrated/dried fruits (variety mix)
fruity cheerios (froot loops, essentially)
bran flakes
puffed wheat
puffed corn
puffed rice
mini wheats (unfrosted)

and occasionally for fun I'll throw in animal crackers or teddy grahams, something small but tasty, as a treat. Scatter the sweet stuff or use them strictly as treats, otherwise they'll decide to hold out and wait for the "good" stuff and waste the rest of the mix.

For fresh foods, you can give them some cooked meats and steamed or fresh veggies/fruits (avoid onion, raw sweet potato & raw potato), cooked rice, and I even give my ratties some of the leftover mashed potatoes from our dinners. Corn on the cob (or just whatever you have left from eating corn on the cob) is also a fun food.

Good luck!