Excellent answer. Let me just add. You staked on a fork that was soon (2min after) abandoned. In bitcoin mining this would be called orphaned or unconfirmed block. The fork may have just been created with your stake. This is actually quite common.
The block was not accepted by miner of the next block and these are most probable reasons:
- someone staked with more coins at about the same time
- your network connection was interrupted for a moment
- you actually were on a (weaker) fork
- it was rejected as invalid (this used to be common due to bug, but no longer is)