[web2py] Question about powertable error

[tomt]

Hi,

I am using powertable to display a subset of a table's rows:
    ...
    id=request.args(0)
    tasks=db(db.task.cparef==id).select(db.task.ALL)
    table = plugins.powerTable
    table.datasource = tasks
    ...

This works just fine, but when I try to specify the columns
    table.columns = ['tasks.title']

I receive the following error:   'something wrong in Rows object'

Any suggestions?