relaxed energy scan with MP4 in G94

 Dear CCL'ers,
 I would like to calculate relaxed energy scan (potential energy curves)
 for some bonds in small molecules, for example for C-Cl bond in CH_3 Cl
 or for C-Br bond in CCl_3 Br, using G94. Some from you wrote me how to
 do such relaxed energy scan. Following job can do it for SF_6
  #p ump2/6-31g* opt=addredundant
  sf6 calculation
  0 1
  s1
  f1 s1 2.7
  f2 s1 1.595 f1 90.0
  f3 s1 1.595 f1 90.0 f2 90.0
  f4 s1 1.595 f1 90.0 f2 180.0
  f5 s1 1.595 f1 90.0 f2 -90.0
  f6 s1 1.595 f2 90.0 f1 180.0
  1 2 1.2 s 30 0.05
 This job scans the distance between s1 and f1 from 1.2 30 steps by 0.05.
 But if I want to use UMP4 instead UMP2, it does not work again. Could you,
 please, write me how to do relaxed energy scan with MP4 ?
 What other options should I use ?  In the guide to Gaussian it is
 proposed to use GUESS=(ALWAYS,MIX) option. What other options are
 necessary at the calculation of such relaxed energy scans ?
                          Thanks,
                                  David
 Dr. David Trunec
 Dep. of Physical Electronics
 Faculty of Science
 Masaryk University
 Kotlarska 2
 611 37 Brno
 Czech Republic
 E-mail trunec at.at sci.muni.cz
 Fax: +42-5-41211214
 Tel: +42-5-41129430