Edit in Photoshop: Metadata gone!

Question

I wonder: is this a bug or is there something wrong with my installation?
OS X 10.5.6, LR 2.2, PS CS 4
If I select "Edit in Adobe Photoshop CS4..." for RAW files that have their metadata appended IN Lightroom, the metadata is gone in Photoshop (checked with "File>File Info...") and of course also in the resulting PDS or TIFF file that's then appearing in LR.
If the RAW file already has metadata inside it (appended with Photo Mechanic or any other application that writes metadata INTO the RAW file), then metadata is preserved and Photoshop WILL show the metadata.
Also, if LR is set up with PS CS4 as the Additional External Editor and this is used with the "Edit in ..." command, the metadata will be preserved.
Has anyone else made similar experiences?
Thomas

Answer 1

Jao, great job, problem solved! Thank you!!
It was a faulty IPTC Date format. This is what I had in LR's IPTC Date field:
2009-03-14 19:15:26
But this is not the correct way of writing it. It has to be:
2009-03-14T19:15:26 or
2009-03-14T19:15:26-04:00 (if I want to indicate that the time was EDT, Eastern Daylight Time and 4 hours behind UTC)
If written like that, Bridge will also show the time (in the first example without the "T", Bridge only showed the date), although it won't show the UTC offset.
If exported to Photoshop CS4 with "Edit in Photoshop CS4" Photoshop now shows all the IPTC data although it strips the time. Back in LR the time will be gone as well (obviously).
Why Photoshop CS4 doesn't accept the time in this IPTC field and why Bridge rather uses a local representation (3/14/2009, 7:15:26 PM) is another story.
So again for all those who do not want to read all of the above:
The IPTC Date was in a bad format and thus ALL IPTC metadata got stripped on its way to Photoshop.
Thanks again, Jao!
Thomas