What can I do about it?

The other day, I was asked whether I'm interested to go for a overseas working trip for 2-3 months, best of all, it was to Sydney! I was elated, I remembered I said 'yes'.

But, later in the week, I saw any email forwarded to me, it said that my boss was against it, because I'm much needed in the project, I'm too important to leave the team at this time. I know then, my boss' boss tried to persuade him, so that I can move on and go on the trip, after that, there was no news. So disappointed!

I have always wanted to go overseas to work on sometime different from what I'm doing now, but when the opportunity comes knocking, I just don't have the luck to get it!