Installing RHEL6 as PV guest under RHEL5 Xen fails with "RuntimeError: Couldn't find xen kernel for Red Hat Enterprise Linux tree."

Issue

• Below error message is triggered while trying to install RHEL6 as a paravirtualized guest under RHEL5 Xen host. The installation procedure is explained in this documentation : http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/sect-Virtualization-Installing_Red_Hat_Enterprise_Linux_5_as_a_para_virtualized_guest.html

  Unable to complete install 'exceptions.RuntimeError Couldn't find xen kernel for Red Hat Enterprise Linux tree.
  Traceback (most recent call last):
    File "/usr/share/virt-manager/virtManager/create.py", line 724, in do_install
      dom = guest.start_install(False, meter = meter)
    File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 539, in start_install
      self._prepare_install(meter)
    File "/usr/lib/python2.4/site-packages/virtinst/Guest.py", line 594, in _prepare_install
      meter = meter)
    File "/usr/lib/python2.4/site-packages/virtinst/DistroInstaller.py", line 245, in prepare
      self._prepare_kernel_and_initrd(guest, distro, meter)
    File "/usr/lib/python2.4/site-packages/virtinst/DistroInstaller.py", line 194, in _prepare_kernel_and_initrd
      type=self.os_type, distro=distro)
    File "/usr/lib/python2.4/site-packages/virtinst/OSDistro.py", line 156, in acquireKernel
      scratchdir, type, distro)
    File "/usr/lib/python2.4/site-packages/virtinst/OSDistro.py", line 142, in _acquireMedia
      return (store.acquireKernel(guest, fetcher, progresscb),
    File "/usr/lib/python2.4/site-packages/virtinst/OSDistro.py", line 253, in acquireKernel
      raise RuntimeError(_("Couldn't find %(type)s kernel for "
  RuntimeError: Couldn't find xen kernel for Red Hat Enterprise Linux tree.'