How to get genomic coordinates from a fasta file

Question

Since there was update the reference genome, I had to get the fasta from the old sequences (from a bed file) to find the new coordinates in this last release.

So, from my fasta file named "my.fasta", (with 35 sequences)

I created a "DNAStringSet" object following this:

 library ("GenomicRanges")
 setwd("/pwd")
 pwd  <- "my.fasta" #INPUT FILES- BedFiles, FASTA, etc.
 path <- system.file("pwd", package = "rGADEM")
 FastaFile <- paste(pwd, path, sep = "")
 Sequences <- readDNAStringSet(FastaFile, "fasta")
 Sequences

 A DNAStringSet instance of length 35
     width seq                                              names
 [1]   300 TTCAGATTGGAGATGGTGAATGA...AACCCTCTGCATAGAATCATAG
 [2]   300 GTCTCCCTTCGTGGAGGGGTCAC...TTAACTGAAGATGTTTCCCCGT

And finally, I tried to use rGADEM to extract the coordinates from my fasta:

library("rGADEM")
gadem <- GADEM(Sequences, verbose = 1, genome = Ggallus)

startPos(gadem)
Error in x@motifList[[i]] : subscript out of bounds
endPos(gadem)
Error in x@motifList[[i]] : subscript out of bounds

Bud didn´t work. How can I extract the coordinates from my fasta file? I need a IRange, bed or something like that. Thank you.