You may see the following error message when you run the ModelSim® -Altera® software version 6.1d if you have a floating license and the mgcld license daemon is too old:
Unable to checkout a license. Make sure your license file environment variables are set correctly and then run 'lmutil lmdiag' to diagnose the problem. Modelsim-Altera uses the following environment variables to check the licenses (listed in the order of preference) 1. MGLS_LICENSE_FILE 2. LM_LICENSE_FILE.
The mgcld daemon included with the Quartus® II software version 6.0 in <Quartus II installation directory>\win is version 8.2, which is too old. The correct daemon is provided beginning with the Quartus II software version 6.1.
To use the ModelSim-Altera software version 6.1d, you should use version 9.5 of the mgcld daemon included with the ModelSim-Altera software version 6.1d. The mgcld daemon is in <ModelSim-Altera installation directory\win32aloem. If you need the mgcld daemon for a different operating system, download the appropriate file at the License Daemon Downloads web page.