Problem with persistence

It doesn't seem to like the

persist add uie $uid

call. I'm getting the following error in the log:

 

 

TCL error: Rule UID_Persist - Prerequisite operation not in progress (line 1) invoked from within "persist add uie $uid"

 

 

Can anyone help me out here? I have no idea what that error means.

 

 

Here's the iRule code I currently have:

 

 

when CLIENT_ACCEPTED {
  set add_persist 1
}
when HTTP_REQUEST {
  set fulluri [HTTP::uri]
  set uid [findstr [HTTP::uri] "uid=" 5 "&"]
  if { $uid != "" } {
    if { $add_persist } {
      log local0. "Adding persist value to table: $uid | $fulluri"
      persist add uie $uid
      set add_persist 0
    }
    else {
      log local0. "Set persist value to uid: $uid  | $fulluri"
      persist uie $uid
    }
  }
  else {
    log local0. "No uid found in HTTP REQUEST  | $fulluri"
  }
}