Formula in Excel not recognizing other named formulas

Hey y'all-

I'm new to this site and was really hoping someone could help me with this one.

I've got an Excel 2003 sheet where column E has a 6-digit code input into it. I'm able to right a function off that code that outputs if E2 (for example) equals 123456 then H2 outputs "Dog," if E2 equals 123457 then H2 outputs "Cat," and so on until I reach the max of 7 nested functions. Problem is, I have a lot more than 7 codes that I need to analyze. This Excel sheet will be used every two weeks, with lots of codes input that need to have what the code means output. I created a named formula called "part1" where:

=if(sheet1!E2=123456,"Dog",if(sheet1!E2=123457,"Cat", etc. It didn't work when I had $ in front of E & 2.

All variables in "part1" work when tested where H2 = part1

I created a "part2" with more variables, checked each and it works too.

My problem now is that when I have H2 set to =if(part1,part1,part2) to test all the variables, it'll work on any variable in "part2" but not in "part1."

Any help would be much appreciated!