This has to do with how the Google Analytics API returns data. The API will only return sessions where all the values are non-null, so when you add something like "Event Label", you're suddenly restricted only to sessions that performed an event, as those are the only sessions where that dimension will not be Null.
The best way I've found to get around this is to have multiple data sources connected to GA for a given workbook, each one focused on a different aspect of the site. For example, one for session-level information, one for page-level information, another for event information, etc.
Thanks a lot James, I understood GA is a cubical data while Tableau creates a 2D image of that data. And your suggestion worked well
But, another problem I face now, can I somehow apply the same filter on two different data sources like one with event label and the one excluding event labels.
It depends on what you're trying to filter.
What you can do is a data blend between two of your data sources ([Date] is usually the best dimension to link the sources by), and then try your filter. Whenever you do this, I highly recommend recreating the same numbers in Google Analytics itself, to ensure your filter and data blend are doing what you're wanting them to do.
Thanks James for the direction, as suggested I used data blend feature and then used parameters to use them as filtering across data source.
But I am not able to do a multi-select in the parameter selection. Is that the best way to go or any work around for multi-section in parameters.
I apologize for the delayed response. You are correct; there is no way to do a multi-select on a parameter. However, you shouldn't have to use a parameter to filter on a variable from a blended source. You can pull those variables onto your worksheet and use them just like a variable from your primary source.
Thanks James.. for your reply. But my issue got solved as I got upgraded to Tableau 10. It is a lot improved, gives you filtering capabilities across multiple data sources.