Last year I bought an insect hotel at the local supermarket (see in the photo below on the right hand side). It was a cheap and simple one, but soon a lot of all different kind of bees came and occupied almost all places, laying eggs and covering the holes with clay.
Because it was so popular among the insects in our garden, I had the idea of making another one myself (see left hand side). I took a piece of wood that had been drying outside for 1-2 years, drilled a lot of holes of different diameters, each a few centimeters deep, and hung it next to the first one.
To my astonishment, not a single bee made use of this new insect hotel. The same this year: in the first sunny days of early spring a lot of bees are flying in and out the insect hotel from the supermarket, but only sometimes a bee would approach the one that I made, only to fly away after short inspection.
What is wrong with my insect hotel?