Calling a module name from a dynamic variable

Hi all, Freeradius 3.1 from git. Just wanted to know if I can do this : Update control { Tmp-String-0 := "mymodule" } "%{control:Tmp-String-0}" { Fail =1 } Hopefully it's obvious - I want to prepare a variable and call a matching module name from the variable, in this case mymodule. It doesn't work at the moment as the string isn't evaluated - it just says: Failed to find "%{control:Tmp-String-0}" as a module or policy. If I can't, I can't no worries, I would just stop me searching if I knew. Thanks Andy