hi,of course, i should have included the versionphenix.version_1.9-1692 the pdb has done more digging and included this comment "Aside from the asym_id, there is another way we use for the mapping, _atom_site_anisotrop.id should map(for ANSIO) to _atom_site.id(for ATOM). This is one-by-one match for each atom. If you look at the file, you see that in the ATOM section, you have ATOM 99999 N3 . U . 367 ? -23.56200 29.36600 106.68800 1.000 135.52000 N ? UC ? 11964 1 ATOM 100000 C4 . U . 367 ? -23.35700 30.62600 106.16100 1.000 133.22000 C ? UC ? 11964 1 But in the ANISO section, you have 99999 N3 . U . 367 ? 2.04230 1.43260 1.67410 -0.19220 -0.28280 -0.16500 A0000 C4 . U . 367 ? 2.00150 1.41600 1.64420 -0.1 8730 -0.28010 -0.16450 i.e. the atom No. after 99999 is inconsistent between the two sections. The ANISO should use 100000. " thanksjpd