RTC 4.0.4 zimport - CRHTC0604E An error occurrec while creating zFolder PRP -- why

We have a mapping file consisting of 15 C records and 10,000 P records - each P record defining a specific pds dataset member (no generics). The 10,000 P records are subdivided between the 15 C records, the 15 subgroups each related to a separate PDS. Each subgroup of P records specifies the same zComponent project and a folder of PRP. There is a corresponding C record for each of unique zComponent project that defines a unique component. So we end up with 15 unique components each with a unique zComponent project. We have used this process a number of times successfully. All seems totally in order but each time we run we end up with the following error:

Problem running 'zimport'
CRHTC0604E An error occurrec while creating zFolder PRP
CRHTC0425E An error occurrec while creating zFolder PRP
See log for details

The log does not provide any additional information. Each time this is run we get a repository workspace created along with two components. One component has a repository file structure with a PRP folder and has an assigned dataset definition. The second component has a repository file structure and no PRP folder.

Question: Can anyone elaborate on the specific condition and/or conditions that would case this failure and that specific error message to be displayed.