There's no way to know what's wrong with the rules file 'cause it could be just about anything, i.e. missing comma, extra comma, unknown tech, etc. You've got to do some basic debugging. Here's how:
1) Copy small sections of your rules.txt (copy1)and paste them into a copy of rules.txt (copy2) that you know works.
2) Load up civ using copy2 of rules.txt.
3) If it works, repeat steps 1 & 2 with the next section. If it doesn't work, you've now isolated the problem section (or one of several problem sections). Repeat steps 1 & 2 with a smaller portion of the problem section.
Make sense?