2.4 shards with 2.6 config servers causing error with split chunk

2014-02-25T22:18:56.469+0000 command { "split" : "test.tmp", "middle" : { "_id" : -10 } } failed: {

	"cause" : {

		"ok" : 0,

		"errmsg" : "Error locking distributed lock for split. :: caused by :: 13663 exception creating distributed lock test.tmp/ip-10-231-1-143:30000:1393366736:1347825563 :: caused by :: SyncClusterConnection write op failed: localhost:29000: { lastOp: Timestamp 1393366736000|8, connectionId: 14, updatedExisting: true, n: 1, syncMillis: 19, writtenTo: null, err: null, ok: 1.0 } localhost:29001: { lastOp: Timestamp 1393366736000|8, connectionId: 14, updatedExisting: true, n: 1, syncMillis: 17, writtenTo: null, err: null, ok: 1.0 } localhost:29002: { lastOp: Timestamp 1393366736000|8, connectionId: 14, updatedExisting: true, n: 1, syncMillis: 33, writtenTo: null, err: null, ok: 1.0 } "

	},

	"ok" : 0,

	"errmsg" : "split failed"

} at src/mongo/shell/shardingtest.js:557