Exchange 2000 Loadsim

HI,
I've tried to use Loadsim ver 6.0.4612.0. My Exchange configuration is two virtual Exchange 2000 sp3 servers on an A-A cluster. I'm testing one virtual server with one storage group (one PF store , one Mbox Store inside).
Tests are performed, as yet, on one client computer Win 2000 Pro sp3, Outlook 2000 SR2 (9.0.0.3821), Outlook is a default e-mail client.
Everything goes smoothly (including creating users in AD) until I run "Initialize Test". The information goes as follows

...
Sep 12 09:52:25: Creating new profile "P352jzvaaa"...
Sep 12 09:52:25: Creating new profile "P352jz3aaa"...
Sep 12 09:52:25: Creating new profile "P352jzfcaa"...
Sep 12 09:52:26: ERROR: P352jzvaaa: Logon or Init failed after 3 tries (E_FAIL).
Sep 12 09:52:26: EVS0-outl2: ERROR: User Init. failed: (43000), bail ..
Sep 12 09:52:26: ERROR: P352jzncaa: Logon or Init failed after 3 tries (E_FAIL).
Sep 12 09:52:26: EVS0-outl9: ERROR: User Init. failed: (43000), bail ..
Sep 12 09:52:26: ERROR: P352jz3aaa: Logon or Init failed after 3 tries (E_FAIL)
...

Any hints much appreciated,
regards, Jo