Error in CSV import

I have a blocking problem in a CSV import, with the following error:

Fatal error: Call to a member function getSymbol() on a non-object in ...../administrator/components/com_hikashop/helpers/import.php on line 491

The platform I use has the following features:

PHP 5.2.4-2ubuntu5.17
Joomla 1.5.22
Hikashop Essential 1.5.8

Note that, on the same server, I have an other Hikashop with correct CSV import capability, but with Hikashop 1.5.7 Business

That error means that it's highly possible that you're missing either the administrator/components/com_hikashop/helper/weight.php file or the administrator/components/com_hikashop/helper/volume.php file. Could you check on them ?

OK. Correct.
I had to do the manual installation and transferring via ftp in the tmp directory the hikashop files, weight.php resulted at 0 bytes.
Thanks for your excellent support - as usual.