Index is not an integer

[Franks Andy (IT Technical Architecture Manager)]

Hi all,
Is there a way of doing this or its equivalent? I'm tracking the index of a variable via expr and then trying to get the output of other variables respectively - I need to do this via a changing index that's housed in a variable, but (and I may be doing this wrong) FR won't start with the following:

    update control {
      Tmp-Integer-0 := 0
    }
    foreach &control:Tmp-String-1 {
      # send the disconnect
      update control {
        CoA-Failure-Reason !* ANY
        CoA-Acct-Unique-Session-Id := "%{Foreach-Variable-0}"
        CoA-Acct-Session-Id := &control:Tmp-String-2[&control:Tmp-Integer-0]
        CoA-User-Name := &control:Tmp-String-3[&control:Tmp-Integer-0]
      }

/usr/local/etc/raddb/policy.d/sql_active_device_disconnect[40]: CoA-Acct-Session-Id
/usr/local/etc/raddb/policy.d/sql_active_device_disconnect[40]:                       ^ Array index is not an integer

.. &control:Tmp-Integer-0 is an integer, unless it's really a string in disguise..

Thanks again, sorry for posting so much.
Andy