I'm having the same problem while trying to add a 2008 license to my 2005 license. Here is my log file:
13:23:57 (lmgrd) pid 5036
13:23:57 (lmgrd) Detecting other license server manager (lmgrd) processes...
13:23:58 (lmgrd) Done rereading
13:23:58 (lmgrd) FLEXnet Licensing (v11.4.0.0 build 31341) started on Fs02 (IBM PC) (1/23/2008)
13:23:58 (lmgrd) Copyright (c) 1988-2006 Macrovision Europe Ltd. and/or Macrovision Corporation. All Rights Reserved.
13:23:58 (lmgrd) US Patents 5,390,297 and 5,671,412.
13:23:58 (lmgrd) World Wide Web: http://www.macrovision.com
13:23:58 (lmgrd) License file(s): D:\Operations\Company Shared Folders\Autocad\ADT Network Version\License\ARCHDESK2005Fs02.lic
13:23:58 (lmgrd) lmgrd tcp-port 27000
13:23:58 (lmgrd) Starting vendor daemons ...
13:23:58 (lmgrd) Starting vendor daemon at port 2080
13:23:58 (lmgrd) Using vendor daemon port 2080 specified in license file
13:23:58 (adskflex) FLEXnet Licensing version v10.8.0 build 18869
13:23:58 (adskflex) lmgrd version 11.4, adskflex version 10.8
13:23:58 (adskflex) Server started on Fs02 for: 46700ARCHDESK_2005_0F
13:23:58 (adskflex) 54800REVSU_2008_0F PLIST
13:24:08 (adskflex) Vendor daemon can't talk to lmgrd (Cannot read data from license server system. (-16,287))
It looks like the 2005 license is doing fine, but something's wrong with the 2008 section.