ESXi installation on USB key onto Microserver Gen 8

[Diablo54800]

Hi,

I've bought a new Microserver Gen8  for personnal use to complete my NAS collection (HP N54L with ESXi and XPenology and a Synology DS212).  

I've receive it yesterday and since, I have an ESXi installation issue.

I've download from HP Website last ESXi version (5.5 Update 2 ) and made an USB Key installation with Unetbootin (and also Rufus software). I can boot on it and perform the installation onto an internal USB Key (8Gb Sandisk Cruzer Blade). Once done, the installation programm ask me to remove the installation disk before rebooting.
But after the reboot, the Proliant don't found any boot disk. If i unplug the Sandisk key and plug it onto my MacbookPro retina, I can boot on it.

If I try to install ESXi onto HDD, no problem for installation and reboot....

I really don't know what can I do to use ESXi onto my USB Key...

For information, my BIOS is J06 : 11/09/2013 and all my firmware are Up2Date (I do the update thru HP Intelligent Provisioning / Perform Maintenance / Firmware update).

Could you please help me ? 

Thx in advance

Rgds,

A French Geek :)

[Diablo54800]

I've found the problem : my USB key.... 
I change it for an other and no problem....don't unterstand what's wrong with it....