Thanks to A Thomas for his solution. Here is his message : Hei Stephanie, You say you did not succeed in loading initial values. Did you get an error message? If so what did the error message say? Note that a prior is may not be defined for each component of delta. If no prior is defined for a component of delta that component must be given an NA in the initial values. I think you can use the node info tool to see which components of delta have a prior (after compiling the model type delta in the node info dialog box and then click on the node button) Moi Andrew With the following initial values, the model runs : list(d=c(NA,0,0,0,0,0,0,0,0,0), sd=1, mu=c(0,0,0,0,0,0,0,0,0,0,0), delta=structure(.Data=c( NA,0,NA,NA,NA,NA,NA,NA,NA,NA, NA,0,NA,NA,NA,NA,NA,NA,NA,NA, NA,NA,0,0,NA,NA,NA,NA,NA,NA, NA,NA,NA,NA,0,NA,NA,NA,NA,NA, NA,NA,NA,NA,NA,0,NA,NA,NA,NA, NA,NA,NA,NA,NA,NA,NA,0,NA,NA, NA,NA,NA,NA,0,0,NA,NA,NA,NA, NA,NA,NA,NA,NA,NA,0,NA,NA,NA, NA,NA,NA,NA,NA,NA,NA,NA,0,NA, NA,NA,NA,NA,NA,NA,0,NA,NA,NA, NA,NA,NA,NA,NA,NA,NA,NA,NA,0), .Dim=c(11,10))) Thanks Stéphanie ------------------------------------------------------------------- This list is for discussion of modelling issues and the BUGS software. For help with crashes and error messages, first mail [log in to unmask] To mail the BUGS list, mail to [log in to unmask] Before mailing, please check the archive at www.jiscmail.ac.uk/lists/bugs.html Please do not mail attachments to the list. To leave the BUGS list, send LEAVE BUGS to [log in to unmask] If this fails, mail [log in to unmask], NOT the whole list