[vw7.4]Localised application does not always show localised strings

Using my application, it often shows the proper localised strings in menu's etc., but sometimes it does not, but shows the english strings from the C Locale.

I have tried solving this by setting the cache to a higher number (500) but that did not have any effect. How can I proceed to have proper localised behaviour?

Some more info: the user message catalogs are four in number, there is a visualworks directory with localised messages also. The folder structure is as follows (for the Dutch locale):

messages

  sepher 

  visualworks

    C

    nl_D