title: RDS instance access from Ec2 instance from different region
body: <p>I have following setup on AWS</p>
  
  <ul>
  <li>One RDS instance in Region 1.</li>
  <li>One Ec2 instance in Region 2. </li>
  <li>EC2-Security Group sgrg2 in Region 2. </li>
  </ul>
  
  <p>I am trying to access RDS from EC2 by adding Security Group to RDS instance list. It is not authorizing.  </p>
  
  <p>Moreover, while adding sgrg2 to RDS security group, it is saying ' EC2 security group sgrg2 for account xxx does not exist'. </p>
  
  <p>Please help. </p>