The centre of the global  map is X 256, Y 512

I am guessing that you are somewhere on the edge of the map it could be left or right , up or down from these co-ordinates ,so you will have to move  a fair way from where you are to see other invaders.

At the top of the page to the right of the name of your kingdom is a target symbol, click on this, and type in these numbers  for  X 410, for Y 329, hopefully you might spot some level 2 invaders around there.

If you have just started playing you will need to increase your knowledge level in order to be able to attack even level 1 invaders  and progress  similarly from there .