Problem entering Line Numbers

When I try to enter line numbers in either the classic input or the list worksheet the entry is deleted when I leave the element and when I return it is "unassigned".
My co-worker started the job and entered the line numbers. If he opens the file the numbers show. Also if I drop down the box in the piping input all the line numbers are there, but if I select one it vanishes each time. Has anyone else seen this or have any ideas?

Caesar2 2011 5.30.01
64 bit Vista

Thanks,
Chris

The first thing to do is update your installation to either 5.30.03 or 5.31.

I have updated to 5.30.03 Build 120131 and it almost works. Now when I enter a line number it changes all the elements to that line number and turns them all to red in the list window. If I enter another value in another element it changes all the elements above and below to the new entry.
This is puzzling.
If I start a new file it all works properly. I will work around this by splitting the isogen at certain nodes however it is not as elegant.
CW

When was this job first created, what build of 5.30? If it was 5.30.00, then the line number ID, saved in the input file was not correct. This has been fixed, but there is no way to correct the line number ID.

There is a work-around: export the model to a c2 neutral file, then import the neutral file into a new job. You should be able to set the line numbers after this.

It was started with an older version, probably 5.30.00. Your work-around was successful. Many thanks.
CW