I am trying to pass a "main" argument to plotPCA so that the title is customized. When I try to do this, I receive an error message "Error during wrapup: formal argument "main" matched by multiple actual arguments". See my code and sessionInfo below. Can I pass "main" as as an argument to plotPCA? Thanks, Mark plotPCA(eSet, groups, groupnames, pcs=c(2,3), addtext = addtext, main="test title") sessionInfo() R version 2.6.0 Under development (unstable) (2007-06-30 r42095) i686-pc-linux-gnu locale: LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US .UTF-8;LC_MONETARY=en_US.UTF-8;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US. UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8 ;LC_IDENTIFICATION=C attached base packages: [1] splines tools stats graphics grDevices utils datasets [8] methods base other attached packages: [1] affycoretools_1.9.2 annaffy_1.9.1 xtable_1.4-6 [4] gcrma_2.9.1 matchprobes_1.9.10 biomaRt_1.11.4 [7] RCurl_0.8-1 XML_1.9-0 GOstats_2.3.8 [10] Category_2.3.16 genefilter_1.15.9 survival_2.32 [13] KEGG_1.17.0 RBGL_1.13.3 annotate_1.15.2 [16] AnnotationDbi_0.0.86 RSQLite_0.6-0 DBI_0.2-3 [19] GO_1.17.0 limma_2.11.9 affy_1.15.7 [22] preprocessCore_0.99.12 affyio_1.5.6 Biobase_1.15.23 [25] graph_1.15.10 loaded via a namespace (and not attached): [1] cluster_1.11.7 -- --- Mark W. Kimpel MD ** Neuroinformatics ** Dept. of Psychiatry Indiana University School of Medicine 15032 Hunter Court, Westfield, IN 46074 (317) 490-5129 Work, & Mobile & VoiceMail (317) 663-0513 Home (no voice mail please)