"The specified agent does not exist"

I have made an agent that will be sent in every users mailfiles (will be sent by a notes template upgrade).

I’ll send after a note that will contain a formula :

@Command( [RunAgent] ; “agent name”) or @Command( [ToolsRunMacro] ; “agent name”).

Somehow i get some pilot users that have the error “The specified agent does not exist”. Some time after he click again an the agent run well.

Does anybody have an idea about what could cause this “bug” ?

Thanks

n.b. the agent run in background client thread