SQL Dependency GROUP BY Fails

Hello, I have the SQLDependency working OK (i.e. the notification comes back when the data is changed), however I now want to use an SELECT statement that contains a GROUP BY as follows :-



select [dbo].[Investment].[ClientId]

from [dbo].[Investment]

group by [dbo].[Investment].[ClientId]



As you can see it is very simple and according to the restrictions placed on the statements possible for the notification it seems to fit within the specifications -



http://msdn2.microsoft.com/en-US/library/ms181122.aspx



However when this is submitted it comes back 'Invalid'



Note that the field ClientId (in the above example) is *not* a nullable field as per the rules



I have tried numerous variations on the above (including adding a SUM() which is also within the rules as per the above link), but to no avail. Can anyone tell me why ?



Many thanks

Travis