[.,]
Is the trick 
How to explain my gratitude ? Bacon ?
Adam,
thanks for the confirmation, I knew it would work now

DeBaas, maybe a short explanation for the curious:
starting with version 4 I added custom code to get these flipping progress bars for all kind of things showing up. Also here where this error occurred, so what is happening here and what went wrong? At this point in the script we download the full set of packages required for adding the new language. This list depends on the chosen language and the packages currently installed in the system. To get a progress bar for downloading these packages we need to know the total MBs to be downloaded (MBdl), then, while the download is progressing, we monitor the constantly growing additional disk space in
/var/cache/apt/archives/, calculate the percentage wrt MBdl, and then pipe this percentage into the constantly updated Zenity-dialog until we reach 100%. The total size to be downloaded is provided in the second line above the one where the first package is retrieved (marked in green below). The we use
sed to extract this number. And here the error occurred: The old command always worked because this number was always a decimal specified with (depending on the language) either a comma or a dot. Now in Adam's case for some coincidence this number was not a decimal as I expected it (102.0MB) but an integer (102MB). Because the old
sed command looked for a number followed by a comma/dot it did not extract the number but the entire string. Then when you compare a string to a number you get the crash
/usr/bin/addlocale: line 1804: [: Need: integer expression expected
Changing the sed-command to look for a number without the comma or dot made it work again, and the script can continue.
.....
0 upgraded, 21 newly installed, 4 reinstalled, 0 removed and 0 not upgraded.
Need to get 102MB of archives.
After unpacking 147MB of additional disk space will be used.
Get:1 http://debian.ethz.ch pclinuxos/2010/main aspell-manual 0.60.6-10pclos2009 [477kB]
Hope to have explained this in a understandable way.
regards,
-p.
Tomorrow I will work on 4.0-4 which will also get the new automatic update routine from the new lomanager.