Cant join columns and walls

[victorveo]

Hi, I'm new to AutoCAD, I have a little problem.
I do not understand why some columns can not be joined to walls, in some cases it works and in others it does not. What'sthe problem?

[ToanDN]

Can't open your file right now but are the columns architectural or structural? Look like they are a mix of both.

[victorveo]

All are structural