ERROR: In procedure swapon: "/dev/sda1": Invalid argument

[Thierry Micoud <thierrymicoud@gmail.com>]

Hi,
Ive been trying to use a swap partition but as the subject title
indicates i get the following error

ERROR: In procedure swapon: "/dev/sda1": Invalid argument

when i do
#sudo guix system reconfigure /etc/config.scm

this is the config.scm file

    (use-modules (gnu) (gnu system nss))
    (use-service-modules desktop networking ssh)
    (use-package-modules certs  rsync zsh suckless emacs vim tmux wm admin)

      ;; For those that want to use the zsh shell
    (define zsh-location
    #~(string-append #$zsh "/bin/zsh"))
    (operating-system
      (host-name "yuhata")
      (hosts-file (local-file (string-append "/etc/hosts-file")))
      (timezone "Europe/London")
      (locale "en_GB.UTF-8")
      ;; Assuming /dev/sdX is the target hard disk, and "my-root"
      ;; is the label of the target root file system.
      (bootloader (grub-configuration (device "/dev/sda")))
      (file-systems (cons* (file-system
                            (device "root")
                            (title 'label)
                            (mount-point "/")
                            (type "ext4"))
         (file-system
            (device "/dev/sda3")
           ;(title 'label)
            (mount-point "/home")
            (type "ext4"))
                          %base-file-systems))
    (swap-devices '("/dev/sda1"))


      (users (cons (user-account
                    (name "tmx")
                    (group "users")
    (shell zsh-location)
                    (supplementary-groups '("wheel" "netdev"
                                            "audio" "video"))
                    (home-directory "/home/tmx"))
                   %base-user-accounts))

      ;; This is where we specify system-wide packages.
      (packages (cons* nss-certs         ;for HTTPS access
       dwm tmux emacs vim dmenu i3-wm htop
       rsync
                        %base-packages))

      (services (cons* (lsh-service)
      (console-keymap-service "uk")
                      %desktop-services))

      ;; Allow resolution of '.local' host names with mDNS.
      (name-service-switch %mdns-host-lookup-nss))

and this is the relevent output of fdisk -l

    Disk /dev/sda: 232.9 GiB, 250000000000 bytes, 488281250 sectors
    Units: sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disklabel type: dos
    Disk identifier: 0x659d198e

    Device     Boot     Start       End   Sectors  Size Id Type
    /dev/sda1            2048   8390655   8388608    4G 82 Linux swap / Solaris
    /dev/sda2         8390656 385878015 377487360  180G 83 Linux
    /dev/sda3       385878016 488281249 102403234 48.8G 83 Linux

I cant see what im doing wrong
any help, sugestions will be greatly apreciated
Many thnaks
thierry