Clock add?

I am having trouble with the clock add function, could anyone give me an example has to how I would add a number of minutes to the current time

 

 

So far I have tried

 

 

set e [clock add [clock seconds] 10 minutes]

 

 

it returns an error : [invalid option "add" must be: clicks format scan seconds] [add]

 

 

 

that to me says that the add sub-function does not exist, yet the tcl reference says otherwise?

 

 

I am quite new to iRules and Tcl so any help would be appreciated, even if it means a work around.

 

 

 

Brett.