running kdump in Dom0 always ends with status "failed"

Loading kdump
Regenerating kdump initrd ...
Could not find a free area of memory of a000 bytes...
locate_hole failed

According to the Xen Guide I have moved the "crashkernel" option in the kernel line of the boot options

kernel /xen.gz vga=mode-0x317 dom0_mem=2048M crashkernel=64M

Where is my mistake?

Configure kernel core dump capture: