Calibre error - help please

[jesjaspers]

Just updated tothe newest version of calibre(0.6.6) and now have an frozen prs505 with error

unsupported operand type(s) for +: 'NoneType' and 'str'

Traceback (most recent call last):
File "calibre\gui2\device.pyo", line 57, in run
File "calibre\gui2\device.pyo", line 199, in _books
File "calibre\devices\prs505\driver.pyo", line 103, in books
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'


calibre sees the reader but none of the files. the reader screen has frozen