title: Cannot query a shard collection
body: <p>I created a shard with two replica sets. Each replica set have 3 <code>mongod</code> server and they work fine. Also, the <code>mongos</code> server seems to work. Here is it's status:</p>
  
  <pre><code>mongos&gt; sh.status()
  --- Sharding Status ---
    sharding version: {
          "_id" : 1,
          "version" : 3,
          "minCompatibleVersion" : 3,
          "currentVersion" : 4,
          "clusterId" : ObjectId("51c5be46dda9b0a5cd83ad64")
  }
    shards:
          {  "_id" : "s1",  "host" : "s1/RemotePC_1:27017,RemotePC_1:27018,RemotePC_1:27019" }
          {  "_id" : "s2",  "host" : "s2/RemotePC_2:27017,RemotePC_2:27018,RemotePC_2:27019" }
    databases:
          {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }
          {  "_id" : "student",  "partitioned" : true,  "primary" : "s1" }
                  student.grades
                          shard key: { "_id" : 1 }
                          chunks:
                                  s1      1
                          { "_id" : { "$minKey" : 1 } } --&gt;&gt; { "_id" : { "$maxKey" : 1 } } on : s1 { "t" : 1, "i" : 0 }
  </code></pre>
  
  <p>But, when I run any command (insert, find, count, mongoimport) on the <code>student.grades</code> collection I get back this error:</p>
  
  <pre><code>mongos&gt; db.grades.count()
  Sat Jun 22 20:07:00.968 JavaScript execution failed: count failed: {
          "code" : 10429,
          "ok" : 0,
          "errmsg" : "exception: setShardVersion failed host: RemotePC_2:27017 { oldVersion: Timestamp 0|0, oldVersionEpoch: ObjectId
          ('000000000000000000000000'), errmsg: \"exception: all servers down/unreachable when querying: My-PC:57017,My-PC:57018,My-PC:57019\", code: 8002, ok: 0.0 }"
  } at src/mongo/shell/query.js:L180
  </code></pre>
  
  <p>Why? Am I missing something?</p>