This would happen depending on: whether or not the ticket has been issued, booking classes, the period where seat selection is available, types of aircraft, with or without code-share, mileage qualification, and for certain other reasons of airlines. If one of the above applies, you may see a message "Unable to Select", after clicking on 'Seat Assignment'.

There is a known issue where seat assignment does not work due to system limitations between the marketing airline and the actual operating airline. Even if you are able to select a seat by clicking on an icon, it might be rejected on the next screen as "Unable to Select".

Yes, you are. However, please be advised that it may take a while for certain airlines to respond to your change request. When you see the message 'Requesting' after making a change, please reloa" your browser and try again or start it again from log in page. Also, it may be possible that you receive a response from airlines saying "We are not able to satisfy your request."

Seat Assignment' icon is grayed out when there is no available seat to be selected in advance or due to airline's reasons. If this happens, you may not be able to select a seat through My Trip+.

"Please register your mileage number before selecting a seat. However, you may not be able to do a seat assigment in the following occasions: --> if you would like to select a seat for yourself as well as for your companion under the same reservation record yet your companion member status is different from yours --> if you have more than two companions under the same reservation record Please contact your travel agent if one of the cases apply."