Yesterday, our ability to delegate Steem was broken due to some bugs in Steem HF 21 code. These bugs were fixed in HF22 today, and we've processed all outstanding failed delegations. Thanks for your patience as we all work thru the transition process to a better Steem.
For anyone interested in the details of the delegation bug in HF21, you can read more about it here: https://steemit.com/delegations/@steemitblog/delegation-issue