Im pretty noob at houses but i wanna place a tower at a spot but cant.

I can place a houseground 16*14 at this spot and on uo:s homepage they say that a tower is 16*14 but i cant place it. (tried many times)
Is there any probs with placing a tower? thinking of the upperlevel that comes to close to another house?

I cant afford to costumize a house from ground nor i have the time for it. so I want to place a prebuild tower there.

tnx