help:simple bin problem histogram

Hi,
I cannot seem to change the default binning settings for the x axis 
successfully using hist(). I have tried using axis() in conjunction with 
xaxt="n", but I keep getting the error message
Warning message:
parameter "vect" could not be set in high-level plot() function
can anyone help please?

Simon Pickett
Centre for Ecology and Conservation Biology
University of Exeter in Cornwall
Tremough Campus
Penryn 
Cornwall
TR10 9EZ UK
Tel: 01326371852