[ic] Message: Attempt to order missing product code

[Lars Weinrich]

Hi,

I'm new to Interchange and have a Problem with an existing installation:

Very often I can't store products in the cart. I use the same way to store a product, sometimes it works, and sometimes the next second it does not work.

In the error.log in the catalog-directory appears the following Message:
 Attempt to order missing product code: [...]

I've traced the problem and sometimes (when the error occures) the Array $Vend::Cfg->{ProductFiles} is empty (and as a result the array @Vend::Productbase, too).
When there is no problem the ProductFiles-Array contains 'products' and 'variants'.

Informations about the system:
 Interchange V5.7.6
 Perl v5.8.8
 Linux (2.6.18-274.17.1.el5)

Has anybody an idea how to solve the problem? 

Thanks in advance

Lars