[ccp4bb]: CNS topology error

[chernhoe <chernhoe@imcb.nus.edu.sg>]

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I got the following error while trying to execute refine.inp with CNS
1.1 using 2PE as a ligand. I did not have any problems with 1PE, so I am
puzzled that this is happening. Does anyone know how to solve this? I
generated 2pe.par and 2pe.top file using het_dicts. I got the same files
from HICCUP server and also got the same error message.


 -------------------------- Torsion Topology 
   ERROR: There are no suitable base groups.
   This problem can be caused by isolated
   bonding networks with undefined or weak
   dihedral force constants.
   The atoms that cannot be placed in a tree
   are listed below:
    %atoms "B   "-300 -2PE -O1
    %atoms "B   "-300 -2PE -C2
    %atoms "B   "-300 -2PE -C3
    %atoms "B   "-300 -2PE -O4
    %atoms "B   "-300 -2PE -C5
    %atoms "B   "-300 -2PE -C6
    %atoms "B   "-300 -2PE -O7
    %atoms "B   "-300 -2PE -C8
    %atoms "B   "-300 -2PE -C9
    %atoms "B   "-300 -2PE -O10
    %atoms "B   "-300 -2PE -C11
    %atoms "B   "-300 -2PE -C12
    %atoms "B   "-300 -2PE -O13
    %atoms "B   "-300 -2PE -C14
    %atoms "B   "-300 -2PE -C15
    %atoms "B   "-300 -2PE -O16
    %atoms "B   "-300 -2PE -C17
    %atoms "B   "-300 -2PE -C18
    %atoms "B   "-300 -2PE -O19
    %atoms "B   "-300 -2PE -C20
    %atoms "B   "-300 -2PE -C21
    %atoms "B   "-300 -2PE -O22
    %atoms "B   "-300 -2PE -C23
    %atoms "B   "-300 -2PE -C24
    %atoms "B   "-300 -2PE -O25
    %atoms "B   "-300 -2PE -C26
    %atoms "B   "-300 -2PE -C27
    %atoms "B   "-300 -2PE -O28
 %TORSION:TOPOLOGY error encountered: Fatal Topology Error
   (CNS is in mode: SET ABORT=NORMal END)