The atom names have been truncated to four characters in the error messages, as there are still some cases where the code has (unfortunately) not been updated to support eight character atom names. You need to look for atom names which begin with CG2D and not an exact match. The original CGenFF parameter file has these atoms:

Code:
MASS  -1  CG2D1     12.01100 ! alkene; RHC= ; imine C
MASS  -1  CG2D2     12.01100 ! alkene; H2C=
MASS  -1  CG2D1O    12.01100 ! double bond C adjacent to heteroatom. In conjugated systems, the atom to which it is double bonded must be CG2DC1.
MASS  -1  CG2D2O    12.01100 ! double bond C adjacent to heteroatom. In conjugated systems, the atom to which it is double bonded must be CG2DC2.
MASS  -1  CG2DC1    12.01100 ! conjugated alkenes, R2C=CR2
MASS  -1  CG2DC2    12.01100 ! conjugated alkenes, R2C=CR2
MASS  -1  CG2DC3    12.01100 ! conjugated alkenes, H2C=
_________________________
Rick Venable
computational chemist