Thanks Eike. It works fine now. Chris Dr Christian Hicks Senior Lecturer, School of Mechanical & Systems Engineering, Stephenson Building, University of Newcastle upon Tyne, NE1 7RU. Phone: +44 191 222 6238 Mobile 0795 8317804 Fax: + 44 191 222 8600 Homepage: http://www.staff.ncl.ac.uk/chris.hicks