error while using doParallel-foreach in windows OS

Question

I am trying to use doParallel for parallelising my query. I am trying to use the col_funcs function within the same script bsp_functions.R after it has been sourced.

#install.packages("doParallel")
library(doParallel)

cl <- makeCluster(3)
registerDoParallel(cl, cores=1)

path <- ("~/Combined/")

source(paste(path, "bsp_functions.R", sep=""))

res <- bsn(data=data, outcome=outcome)


#bsp_functions.R
bsn <- function(data, outcome){

    rs_fun <- foreach(i=1:length(sets), .combine=rbind) %dopar% {

    list['data.temp', 'sets'] <- col_funcs(data, set)
    }

}

col_funcs <- function(data, set){

    # processing
}

It is giving the below error:

Error:
Error in { : task 1 failed - "could not find function "col_funcs""

After looking at this post, I have changed my code as below by passing the function through .export to global environment.

rs_fun <- foreach(i=1:length(sets), .combine=rbind, .export='col_funcs') %dopar% {

Now, it gave the below error.

Error in { : 
  task 1 failed - "object of type 'builtin' is not subsettable" 

Any help would be appreciated.