[moderator DPsycho: Moved topic to Support section]
Could you provide a link to the replay for the game where it didn't work for you? If the game hasn't concluded yet, you'll have to wait until it has to do so.
WatchtowerLooking at what you wrote, however, I assume you're confusing the difference in "and" and "or" in this case since you wrote "or" when the card states otherwise. To pass the check, there must be at least one Far sight AND at least one Siege in hand. (Both must be >0 as you can see in the card's code in the above link.)
If it failed to happen when both were true, please link the replay so we can see what else was going on at the time. If it was a misinterpretation of the conditions, we'll close the report.