Make sure the source volume you choose when creating a NetRestore image has a Recovery HD partition associated with it.
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Some reasons that a volume might lack a Recovery partition:
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- It is a software RAID volume. Recovery HD partitions are not supported on software RAID volumes. 

- It is a disk image created by Disk Utility from an OS X volume source. Disk Utility effectively removes the Recovery HD partition when creating the image. 

- It is a volume created by restoring such an image created by Disk Utility. 

- It is a volume created by restoring an image created by System Image Utility with the "include recovery partition" checkbox disabled. 

- The Recovery HD partition was manually removed.