I created a tile map layer from something I was working on on ArcGIS desktop to upload to ArcGIS online and show my colleagues. However, when I try to upload it over a basemap, it says that they are in different co-ordinate systems. I have tried different scenarios of re-projecting in desktop to change the co-ordinate system but it still won't display. My vector layers are in the same system and appear fine over the top of the basemap. Was wondering if I'm missing something, or if it is even possible to display a tile layer over a basemap on online?