Lazarus(Pascal) RunError(5) - pascal

Question

My program exits with RunError(5), which would suggest that it can't access the file, which it should be able to. I have checked and the file is used as it should be, the file isn't read-only, etc. What the program does is, it creates a .dat file if one doesn't exists and uses it for saving stuff. If I run the program and the file doesn't exist, the file is created, but after that, in the same execution, the program won't access the file. This ONLY happens if the file was created in the current execution.
This is the way in which the procedures are called(the code is quite long but I am giving you the first few lines, where the error occurs):
fileName := 'labSave.dat';
CreateFile;
assign(labyrinthFile,fileName);
writeln(CheckFileSize);
and then there is each of the procedures:
procedure Initialize;
begin
fileName := 'labSave.dat';
assign(labyrinthFile,fileName);
end;
procedure CreateFile;
begin
if not FileExists(fileName) then FileCreate(fileName);
end;
function CheckFileSize: integer;
begin
reset(labyrinthFile);
CheckFileSize := FileSize(labyrinthFile);
close(labyrinthFile);
end;

Answer 1

According to Lazarus forum (http://forum.lazarus.freepascal.org/index.php?topic=4936.0):
Runtime Error 5 means Access denied. The file maybe readonly and you
use the wrong (default) filemode, or you try to re-open the file with
a new filehandle without having closed it before (somewhere in the
while and repeat loops possibly you assignfile more then once, then
the reset fails?).
If I recall correctly now, the workflow should be as follows for create:
AssignFile(f, filename); Rewrite(f); CloseFile(f);
and for existing file:
AssignFile(f, filename); Reset(f); CloseFile(f);
Seeing other mistakes found in your code through questions in comments, I strongly suggest you to devote more time to debugging and when such errors happen - strip out ALL of the irrelevant code and check your code design for cases like above (assigning file before creating it, etc.).