Receivable Aging - report error

[Norm Scherer]

On Ubuntu 14.04 with GNUCash 2.6.1 (recently upgraded from 2.4 and this 
is the first time I have run this report).

When I run receivable aging I get an error message 'Report error'.  A 
trace file is left in /tmp.  The only significant warning that is 
apparent is that it reports 'WARN <gnc.python> Unable to initialize 
Python module (unable to open
  /usr/share/gnucash/python/init.py)' while the file is there with 644 
permissions.  At the bottom I find the error message:

    In unknown file:
        ?: 0 [apply-smob/1 #<catch-closure 1de62a0> out-of-range ...]
    ERROR: In procedure apply-smob/1:
    ERROR: Value out of range: 5

In the receivable account I find a couple of strange entries with Action 
'Lot Link' and Memo 'Internal link between invoice and payment lots'.  I 
have never seen those before and I did not put them in.

Does anyone know what is going on here and how to correct it?

Thanks
Norm