[modeller_usage] getting pdb's but not fit.pdb's

hey, i'm new to modeller. I can use modeller and and get homology models of proteins but when it comes to writing the superposed pdb's (the x_fit.pdb's) it comes up with an error and doesn't...

i've included the .top, .ali, and .pdb as well as a screenie of the error. any help would be greatly appreciated. thanks heaps -mike