Non character argument in R string split function (strsplit)

This works

x <- "0.466:1.187:2.216:1.196"
y <- as.numeric(unlist(strsplit(x, ":")))

Values of blat$LRwAvg all look like X above but this doesn't work

for (i in 1:50){
  y <- as.numeric(unlist(strsplit(blat$LRwAvg[i], "\\:")))
  blat$meanLRwAvg[i]=mean(y)
}

Because of:

Error in strsplit(blat$LRwAvg[i], "\:") : non-character argument

It doesn't matter if I have one, two or null backslashes.

What's my problem? (Not generally, I mean in this special task, technically)