Why can't i use Elastic Inference in the regions mentioned in the Docs?

It is mentioned in the AWS EI docs that we can use EI in US EAST, WEST, ASIA PACIFIC, EU. But when i launch an instance in ohio or Seoul, it shows this error

Instance launch failed
The Availability Zone [us-east-2c] does not support Elastic Inference Accelerators. Choose another Availability Zone.

Launch log
Initializing requests
Succeeded
Launch initiation
Failed

Why is this happenging?? Is this a problem from my end?