Backup&Recovery 10 ESX Agent error "No license found" though acquired successfully as per License server log

Dear all,

we have licensed Backup&Recovery 10 virtual server edition with deduplication. The licenses have installed without errors and are visible in the license server.

The ESX agent can connect to the license server succesfully and (as per license server log entry) also sucessfully aquires the licenses (i.e. taken at the correct time and taken from the right MAC address and hostname).

Anyway the agent still states "The license cannot be found. Provide a license for Acronis Backup & Recovery 10 Agent for ESX/ESXi"

The temporal license in the trial version went well on our machine (Backup server is a XP SP3 machine, ESX 4.0 SP1) (remind: locally installed license).

My questions are:
1) Do I need the license server anyway or can I provide the license key directly (as during trial version) ?
2) I have deinstalled and installed the software without any changes, what else can I do ?

Note: Our system is in an security zone without internet access, so please do not refer to web installers etc.

Best regards,
Jürgen