[fpc-pascal] Error runtime 102

[Janie Gan]

Hi,

  I've been working on a program and each time i run it, it comes up wiht an 
error runtime 102. I know it might have something to do with Assign, Amend 
etc functions but can't figure out exactly where i went wrong. Here's an 
example script.

Begin
  Assign(oldd,'DDNAMEold.txt');
  reset(oldd);
  REPEAT read (oldd,ystart,yddstart,P);
  UNTIL eof(oldd);
End

I've got this program from another person who's been working on this before 
me. I'm a complete beginner and has been spending a week learning how to use 
Pascal. Would appreciate it if someone can point out where I've gone wrong 
and also how to fix it!

Thank you!

Janie