Unable to add column error

This is my first time using a RAM model and I have run into an error when trying to layout my building. All of my columns go in correctly except for one area where I get the error "unable to add column. column would overlap another column. There is no other column in the specified location in my model. There are columns at the same grid point below this point, but that is the case for all the other columns that do work as well. I would very much appreciate any help. Thanks.