Post Selected Columns into next available column

I am trying to write a macro that copies specific columns and then inserts them into the next available column. This is what I currently have

Sub addnewyear()

    Columns("D:O").Select
    Selection.Copy
    Cells(Selection.Row, Columns.Count).End(xlToLeft).Offset(, 1).Select
    Selection.Insert Shift:=xlToRight
End Sub

I'm getting selection not valid, I believe it's because its not selecting the entire column which i want it to do. Any suggestions? Thanks for the help.

column example.xlsm I couldn't send the exact file because it includes sensitive information but here is something similar to what I am working on, the macro kinda works in this example but its not in the one I'm working in. The macro copies the columns just fine but then fails when it tries to insert, i believe it has to do with the fact

Cells(Selection.Row, Columns.Count).End(xlToLeft).Offset(, 1).Select

selects a cell and not an entire column. is there a way to select the entire next available column and then insert the copied columns there?

Not sure why but now it's working, I didn't change a thing, Thanks for the help