Sum session value from several servers?

[mibo]

Hi all,
I've been trying hard for two days now, but doesn't seem to find how to query to get the following graph:

I have three servers. All three have a performance counter called "Active SMTP Sessions" which returns the following field
"Active SMTP Sessions" = 23

I'd like a graph that shows the total amount of SMTP sessions, a sum of the same performance counter from all three servers.

I've managed to do a timechart showing the three values by host followed by the addtotal, and that's nice.
But I really only want the Total on my chart, not all thre servers plus total.

Any ideas?

[hexx]

This doesn't do the trick?

... | timechart sum(active_SMTP_sessions) AS "Total active SMTP sessions"