Mongo db sharded "the collection's metadata lock is taken" issue coming very frequently

I am seeing this warning in mongoS log consistently for one collection.

[conn96] warning: splitChunk failed - cmd: { splitChunk: "ibeat20150105.dgrpCount", keyPattern: { articleId: 1, host: 1 }, min: { articleId: MinKey, host: MinKey }, max: { articleId: MaxKey, host: MaxKey }, from: "shard0000", splitKeys: [ { articleId: "01a12144225c646875aeea79990432", host: "xyz.com" } ], shardId: "ibeat20150105.dgrpCount-articleId_MinKeyhost_MinKey", configdb: "x.x.x.x:27017,x.x.x.x:27017,x.x.x.x:27017" } result: { who: { _id: "ibeat20150105.dgrpCount", state: 1, who: "ibeatdb61:27017:1420207410:680478249:conn105:432206596", ts: ObjectId('54aa4f1c253720e5ba254fde'), process: "ibeatdb61:27017:1420207410:680478249", when: new Date(1420447516889), why: "split-{ articleId: MinKey, host: MinKey }" }, ok: 0.0, errmsg: "the collection's metadata lock is taken" }

This is coming continuously for one collection. Also when i checked the data distribution this whole data is on one shard only for this particular collection. I check lock with id: balancer it seems to be working fine. as i did not get a time for which it has locked indefinitely.

This is creating load on my primary shard which is impacting write operations. Could you please help me.