“Invalid value for segment.”
I'm using Python 2.7.5 (64-bit)
Pandas 0.12.0
on Windows 8 

I'm trying to access the boolean value 'containsSampledData' per Google documentation here:

https://developers.google.com/analytics/devguides/reporting/core/v3/reference#sampling

so I run:

```
from pandas.io.ga import GAnalytics
gAnalytics = GAnalytics()
z = gAnalytics.create_query(‘web id’, ‘pageviewsPerVisit’, ’2013-08-12′,’2013-08-14′, ‘date, 'segment id'’).execute().get(‘containsSampledData’)
```

but the segment causes this error:

“Invalid value ‘ga:1234′ for segment.”

running this also causes the same error: 

```
gAnalytics.create_query('web id', 'pageviews', '2013-08-12','2013-08-14', 'date', 'segment id').execute().get('rows', [])
```

When I take the segment out, I get the expected results that match the Google Analytics web portal.  The reason I would like to access segments is so I can test a case where I get an expected value of 'true' returned from 'containsSampledData' since segment pretty much always uses sampled data.
