One missed match was for the molecule 4,8bdihydropyrrolo indole-1,3(2H,3aH)-dione (CSD reference code BUVGAC), which displays a large deviation in molecular geometry between the observed crystal and the gas phase optimised geometry used in CSP. Flexibility in the fused ring system allows the molecule to "fold up" in the gas-phase optimisation, sufficiently to change its packing behaviour. As a result, the experimental crystal structure is not a minimum on a CSP landscape derived from the gas-phase conformer. In the case of DNNEPH10 (1,8-dinitroso-naphthalene), we fail to find the experimental structure despite an apparently rigid, planar molecule that changes very little in the gas-phase optimisation. However, even optimising the known crystal structure using our FIT+DMA energy model results in a final structure that does not match, i.e. the experimental structure appears to be unstable at our level of theory. This may indicate a failure of our energy model for a case of somewhat unusual chemistry. Two of the missed matches are unusual cases in which a refcode "stem" (the initial six letters, typically shared by a "family" of multiple CSD entries of the same species) is used by crystal structures containing distinct chemical bonding arrangements. Our procedure takes a single representative of a CSD refcode family as the source for the molecular connectivity, which was assumed to stay fixed. In the case of refcodes XUGHUD/XUHGUD01, there is a tautomeric difference, which led to no match with XUHGUD01. For IHEPUG/IHEPG02, the subject molecule is a diastereomeric fused ring system, which exists in an anti configuration in IHEPUG, but a syn configuration in IHEPUG02. It is arguable that these crystal structures should not be considered part of the same "family", as these distinct bonding arrangements are not interconvertible. CSP was performed with the isomer found in IHEPUG, so no crystal structure matching IHEPUG02 was located. These two systems demonstrate a shortcoming of our approach, in that we assumed that a given CSD refcode "stem" always denotes the same molecular connectivity, including protonation states. Fortunately, these are the only instances of this assumption failing in the entire set. Our final missed match occurs for QIBCEK, benzo(f)phthalazin-4(3H)-one, another rigid planar molecule.