did you check the boxes for wiping data and cache??
what i would recommend is that you stop using RM to dl and install your rom. i can't even begin to tell you how many times RM is the problem in the install process. in fact, i am going to just cut and paste a post i made only within the last hour on this very topic:
you'll get better results by manually flashing in recovery, instead of thru RM. i always, and i mean ALWAYS, manually flash thru recovery. RM has some great uses, but it can be glitchy when it comes to dl'ing and installing roms. and, because you are essentially putting on a whole new OS, you want the process to be glitch free! i ALWAYS use my pc to dl the rom and then put it on my sdcard (and don't dl thru RM). then, here is the process i follow, and it never fails me:
1. backup your apps with TiBu (or thru Astro)
2. create a backup/nandroid of your current rom (so you have something to fall back on if you experience any serious problems flashing a new rom)
3. boot into recovery
4. wipe data/factory reset
5. wipe cache
6. go into partitions menu, and format boot and format system.
7. install rom zip from sdcard
8. reboot
IMPORTANT – after you sign into Google, and Google syncs all of your data, do not use your phone until the market completely downloads all your apps. let it complete the process before flashing any themes, kernels, whatever
9. boot into recovery
10. flash theme (if you desire something other than stock)
11. reboot
12. boot into recovery
13. flash kernel (if you want something other than the stock kernel)
14. reboot
15. enjoy!