PROBLEMS:
Some buttons would not work.

BUTTONS:
My personal buttons work, but some AutoCAD's default buttons would not work and give me the error ´ _sheetset unknown command "sheet set" ".

FUNCTIONAL BUTTONS:
New, Save, Open, & Print
NON FUNCTIONAL BUTTONS (Both in my workspace and AutoCAD's workspace):
SheetSet, DesignCenter, Properties, & Tool Palettes Window.

CUI:
Created (New) my personal CUI in the CUSTOMIZE tab.
Created (New) my personal CUI in the TRANSFER tab.
In TRANSFER tab, transferred my personal toolbars to ACAD.CUIX.

WORKSPACES:
Saves As my own workspace.
Reverted to the AUTOCAD CLASSIC & DRAFTING AND ANNOTATION.

MENU:
From the AutoCAD's default menu, enabled the STANDARD toolbar.

AUGI FORUM:
I searched for " _sheetset unknown command "sheet set" ", not post to read.

FOOTNOTE:
All buttons work if I reset AutoCAD. I have done this more than ten times and I am frustrated by now in recreating menus and toolbars and links. I hope I have given enough information to get help.