__func__, ra, tid);
 
        sta_id = iwl_find_station(priv, ra);
-       if (sta_id == IWL_INVALID_STATION)
+       if (sta_id == IWL_INVALID_STATION) {
+               IWL_ERR(priv, "Start AGG on invalid station\n");
                return -ENXIO;
+       }
 
        if (priv->stations[sta_id].tid[tid].agg.state != IWL_AGG_OFF) {
                IWL_ERR(priv, "Start AGG when state is not IWL_AGG_OFF !\n");
        }
 
        txq_id = iwl_txq_ctx_activate_free(priv);
-       if (txq_id == -1)
+       if (txq_id == -1) {
+               IWL_ERR(priv, "No free aggregation queue available\n");
                return -ENXIO;
+       }
 
        spin_lock_irqsave(&priv->sta_lock, flags);
        tid_data = &priv->stations[sta_id].tid[tid];
                return ret;
 
        if (tid_data->tfds_in_queue == 0) {
-               IWL_ERR(priv, "HW queue is empty\n");
+               IWL_DEBUG_HT(priv, "HW queue is empty\n");
                tid_data->agg.state = IWL_AGG_ON;
                ieee80211_start_tx_ba_cb_irqsafe(priv->hw, ra, tid);
        } else {