[Evolution] Can't acces old mails in evolution after debain dist-upgrade, though files are all there

[Martin Lemmen <mlemmen gmx net>]

Hi all, here's my situation:

I (at last succesfully) upgraded my Debian from Lenny to Squeeze

Evolution easily imported all the settings from before the dist upgrade

however, only the mail received since then is displayed
when looking into the .evolution folder, and displyaing Inbox with less,
I saw mails from last fall, however the evolution client only displays
the last few (that I can also find with less in the file)

When I try to Import settings, I get the message no importable messages
found.

Any pointers?