WaitForSeconds does not work

Here is my coroutine :

 IEnumerator SyncLevelCoroutine(LevelData a_level)
 {            
     Network.SetSendingEnabled(0, false);
     Network.isMessageQueueRunning = false;
         
     Network.SetLevelPrefix(1);
     Application.LoadLevel(a_level.m_szLevelName);
         
     while(m_nStatus == EStatus.eSynchronizing)
     {
         yield return new WaitForSeconds(0.1f);
     }
                     
     Network.isMessageQueueRunning = true;
     Network.SetSendingEnabled(0, true);
         
     if(Network.isServer)
     {
         SetReady();
     }
     else
     {
         networkView.RPC("SetReady", RPCMode.Server);
     }
 }

and here is the call of the coroutine :

 StartCoroutine("SyncLevelCoroutine", level);

The coroutine is stopped in the WaitForSeconds statement. I have tried to put a Debug Log before this line, but the log is shown only once. Any log after the while loop is not shown. If I replace "yield return new WaitForSeconds(0.1f)" by "yield return null", it works. Any idea why WaitForSeconds lasts an eternity?