"will not create hard link"

HI, I've a strange message when I'm copying some files and directories: cp: will not create hard link ... Anyone an idea what could be the problem?

Met vriendelijke groet / Mit freundlichen Grüßen / Kind Regards,

H.J. ten Berge Test Engineer HITT Traffic Oude Apeldoornseweg 41-45 P.O. Box 717 NL-7300 AS, APELDOORN The Netherlands Telephone +31-55-543 26 34 Fax +31-55-543 25 53 E-mail mailto:berge@hitt.nl Internet http://www.hitt-traffic.nl