Delphi 1 problems - please help(pt2

3) Again using the same application running on the C:\ drive of
each of the 6 PCs, sharing the control table which tells them
what files to process - I want each PC to process a different
file - the way I avoid them doing this is by having a flag on the
control table set to P when the file is being processed, but what
happens is that the record seems not to be updated on the network
and so the second PC picks up what the first Pc is processing.  
It works the first time eg. The first PC picks up file 1 and
processes puts a P in the record - the second PC reads the
control file and sees that the first file is being processed so
moves onto the second file and puts a P in the flag for that
file(this is the update that seems not to be posted).  THEN the
first PC after having finished processing the first file moves on
to the second file and does not see the P there and therefore
continues to process the same file.  What do you think is wrong?
I have put a Post in after the setting of the flag.  Then I also
do a refresh.  I also do a refresh on the start of the read of
the control table -( read first).
please can someone help

Thanks in advance