Dear Sean, James and Martin, Thank you for your advice. My collegue resolved the problem after noting an earlier error when affyio 1.4.1 was orginally installed (rather than the required 1.5.1) and has just reinstalled it and all of the other biocLite packages. Thanks again Bill W. B. Langdon, Mathematical Sciences, University of Essex Wivenhoe Park, Colchester CO4 3SQ, UK http://www.essex.ac.uk/maths/staff/langdon/ A Field Guide to Genetic Programming http://www.gp-field-guide.org.uk/ CIGPU 2008 http://www.cs.ucl.ac.uk/staff/W.Langdon/cigpu/ GP EM http://www.springer.com/10710 GP Bibliography http://www.cs.bham.ac.uk/~wbl/biblio/

Thanks for following through, Bill. The 'release' version of BioConductor packages have an even digit as the second part (the 'y' in x.y.z) of their version number, so if you're using a current R you probably meant 1.6.1. For what it's worth, this is one reason why sessionInfo() can be so useful -- does the version of the package match the version of R and BioConductor? Assuming you're using the current released version of R, an easy way to check for yourself is to compare package versions reported by sessionInfo() with the version numbers on the pages linked from the 'Packages' link of http://bioconductor.org. And then to update packages, if necessary, using instructions on http://bioconductor.org/download. Thanks again, Martin Langdon W B wrote: > Dear Sean, James and Martin, > Thank you for your advice. > > My collegue resolved the problem after noting an earlier error when > affyio 1.4.1 was orginally installed (rather than the required 1.5.1) > and has just reinstalled it and all of the other biocLite packages. > > Thanks again > > Bill > > W. B. Langdon, > Mathematical Sciences, > University of Essex > Wivenhoe Park, > Colchester CO4 3SQ, UK > http://www.essex.ac.uk/maths/staff/langdon/ > > A Field Guide to Genetic Programming > http://www.gp-field-guide.org.uk/ > CIGPU 2008 http://www.cs.ucl.ac.uk/staff/W.Langdon/cigpu/ > GP EM http://www.springer.com/10710 > GP Bibliography http://www.cs.bham.ac.uk/~wbl/biblio/