pvcreate error 241 for loopback devices

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-------- Original Message --------
From: Scott Sexton & David Lewis <[email protected]>
Subject: pvcreate error 241 for loopback devices

I'm very sorry for this question as the answer must be obvious.

While trying to use the loopback device with files for testing lvm, pvcreate is giving me this
error -241 getting size of physical volume "/dev/loop0".

Do I need something besides lvm to use loopback devices with it?