The function getCaption <- function(k) as.graphicsAnnot(unlist(caption[k])) inside plot.lm in R-2.9.2 and R-2.10.0alpha loses the expression for caption 6. From a recover() inside the function Browse[1]> caption[6] [[1]] expression("Cook's dist vs Leverage " * h[ii]/(1 - h[ii])) Browse[1]> caption[[6]] expression("Cook's dist vs Leverage " * h[ii]/(1 - h[ii])) Browse[1]> getCaption(6) [[1]] "Cook's dist vs Leverage " * h[ii]/(1 - h[ii]) Browse[1]> as.graphicsAnnot(caption[[6]]) expression("Cook's dist vs Leverage " * h[ii]/(1 - h[ii])) The repair seems to be to redefine getCaption as follows Browse[1]> getCaption <- function(k) as.graphicsAnnot(caption[[k]]) Browse[1]> getCaption(6) expression("Cook's dist vs Leverage " * h[ii]/(1 - h[ii])) Browse[1]> Rich