The empty value at the given location (PID[1].3[2].4.1) in the message does not match a non-empty value.
The empty value at the given location (PID[1].3[2].5) in the message does not match one of the expected values 'SS'.
Looking at the data set, PID-3 does not have a second iteration. The example message that can be loaded in the validation tool shows the following:
MR-76732^^^NIST MPI^MR~184-36-9200^^^MAA^SS
It appears that this sample message is incorrect based on the data set.