Some times when I digitise on screen, instead of coordinates comes up as I click I get "NaN", and when I finish digitising a get the message that only one point has been taken. What am a doing wrong? cheers tom 8-) Tom Charnock O--O Dept Civil Engineering (~~~~) Aston University ( __ ) Birmingham B4 7ET UK /|\ /|\ charnotw at sun.aston.ac.uk