R intersection plot

I have two csv files each looking like:

Sample1 Sample2 C C
G G
C C
I uploaded two csv files to R and made an input read list using:

1 <- read.csv(file = "set1.csv", header = TRUE, sep=",") 
2 <-read.csv(file = "set2.csv", header = TRUE, sep=",") 
1 <-as.vector(set1$V1) 2 <- as.vector(set2$V1) 
read_sets <- list(reads1 =1, reads2 = 2)

upset(fromList(read_sets), order.by = "freq")

But it is showing the error Error in start_col:end_col : argument of length 0