No data when setting segment to Paid Traffic (gaid::-4)

[mschenkel]

This query returns valid paid search traffic data:

https://www.googleapis.com/analytics/v2.4/data?ids=ga:xxxxxxx&dimensions=ga:keyword&metrics=ga:adclicks&sort=-ga:adClicks&start-date=2015-02-22&end-date=2015-03-24&max-results=10

It was my understanding that Paid Search Traffic is represented by gaid=-4.  So I would assume that adding condition on segment that it be Paid Search Traffic I should get the same results (or at least some data).  This is because my dimension and metrics only apply for Paid Search traffic.  But instead I get NO data:

https://www.googleapis.com/analytics/v2.4/data?ids=ga:xxxxxxxx&dimensions=ga:keyword&metrics=ga:adclicks&sort=-ga:adClicks&segment=gaid::-4&start-date=2015-02-22&end-date=2015-03-24&max-results=10

Note the only difference between the two is the omission of the segment parameter.

What is interesting is that in the results from the query that includes the Paid Search Traffic segment, I see the following tag:

dxp:segment id="gaid::-4" name="Paid Traffic">
<dxp:definition>
sessions::condition::ga:medium=~^(cpc|ppc|cpa|cpm|cpv|cpp)$
</dxp:definition>
</dxp:segment>

[mschenkel]

Sorry - forgot to conclude with my question: Why when setting the segment to Paid Traffic am I not getting any data?  The data represented by the metrics and dimensions relate only to Paid Traffic data.