Adding a file to an existing CD-R

Greetings all,

I'm using:
Nero Express 6

Win98
Pentium II @ 350mhz

I was able to burn a file from my hard drive onto a CD-R using Nero Express
6.

However, I am having difficulty burning an additional file on _subsequent_
sessions.

My steps were to:

1. Drag file into Interface
2. Hit burn (burn icon on the lower right part of interface)
3. It burns file
4. CD-R ejects after the prompt to save

5. Insert CD-R, the file is there.

6. Go through the same steps as before by dragging another file into the
interface, hit burn, etc.

However, when re-inserting the disc, the orginal file is there but not the
additional one which I thought I just added.

Any help will be greatly appreciated.
Thank you,
TR