Many thanks! Placing vias in auto mode solved the issue.
I think this is a bug in the program. Eagle should be smart enough to allow you to put in the right place the vias in manual mode also.
I have another question please. The rectangle surrounded by the ground in the attached picture it is the end of a transmission line.
I want to connect ONLY this end of the transmission line to the top ground.
I cannot connect this end of the TL to the ground in the schematic, because the program it will put on the layout ALL the sides of the TL to the ground. So I have to do this connection only in the layout mode.
If I use a rectangle or a polygon to do this connection works, but from the moment when I press "ratsnest" this will disappear.
If I use a wire to connect to the ground (as in the picture) works, but I get a "clearance" error.
I have an option to place a vias, but this will connect the end of the TL to the bottom ground, and I want to be connected to the top ground.
I don't know if is any other option.