I deleted a device by hazard and now, I cannot have it back under Netflow Analyzer

I deleted a device by hazard and now, I cannot have it back under Netflow Analyzer

Hi,
 
I am new to Netflow Analyzer. Yesterday, I created about 20 devices and this morning, I have deleted one device by hazard. Whatever I try, I do not succeed in having this device back under Netflow Analyzer. I there somebody who can help me?
 
Many thanks 

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