Maybe one of you may know or guess what I am doing wrong.
This is the text I sent to support:

Dear support team
Printing from capture one 6 gives me prints that are much too dark.
I use my paper profile (made with eye1pro) and of course turn off the printer's color management.
The preview in the print module looks pretty dark, but not as dark as the print.
If I develop the file in capture one and then print the resulting tiff in Lightroom 3 with exactly the same settings and profile, I get a perfect print which matches the screen images both in Lightroom and Capture One. So the color management is ok. Checking or unchecking black point compensation makes no difference.
Of course, I would prefer to keep my workflow, including printing, in capture one which is my program of choice.
Any ideas what may be going wrong?
My printer profiles are in the colorsync folder in the HD library and that is where Lightroom takes them from.
regards, maurice