adding a name to cross tab margins

Listers,

I have created a cross-tab matrix using the following code:

S <-
c(1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,2,3,1,1,2,3,1,1,2,3,1,2,2)
F <-
c(1,2,3,1,2,3,1,1,1,1,2,3,1,1,3,2,2,2,1,2,3,1,1,1,1,2,3,3,1,3,1,3,1,1,2,3,1,1,3,2,3,2,1,1,1,2,3,1,1,2)
table(S,F)
fF <-factor(F, labels = c("Dem","Ind","Rep"))
fS <-factor(S, labels = c("Dem","Ind","Rep"))
PiD <- table(fS,fF)
PiD <- cbind(PiD, margin.table(PiD,1))
PiD <- rbind(PiD, margin.table(PiD,2))

Now I would like to add the Column Name and Row Name "Total" to the last row
and last column (where the marginal totals now hang out). When I use the
command

colnames(PiD[,4]) <- c("total") I get the error:

Error in `colnames<-`(`*tmp*`, value = "WTF") :
?attempt to set colnames on object with less than two dimensions


Since I am still new to R, I can't really understand the error... Can
someone tell me what I am doing wrong here?