problem with rss-feed (always showing only one/last header)

hey there,

I have this following problem, which seems to have to do with DT, as this does not occur in Google Reader nor in Feeldy, with the same feed-url:

whenever I subscribe to a feed of the pattern:
I only see one feed item in DevonThink. when there is a new feed item DT will drop all others, only showing the last single feed-header.

help appreciated!
thanks already