Hector_mapping cannot laser scan into base_frame

Hi guys. Thanks for your attention in advance. I am using hector_mapping with Hokuyo URG-04LX-UG01 and ROS INDIGO. The problem has appeared in other occasions, but following indications of other questions hasn't solved it. So, once again, the problem is, when I run the hector_mapping node and the hokuyo_node at the same time, > $ rosrun hokuyo_node hokuyo_node> $ rosrun hector_mapping hector_mapping it appears this error: > [ INFO] [1469723827.101706930]: lookupTransform base_link to laser timed out. Could not transform laser scan into base_frame. I've seen that the solution goes through changing some parameters in the launch file of the hector_mapping. I've tried but it's still not working. I attach here the **mapping_default.launch** (opt/ros/indigo/share/hector_mapping/launch/mapping_default.launch). Again, thanks a lot. A detailed answer would be super appreciated.