I think you may be wrong on the list line. Just because a business has a no weapons sign doesn't seem to mean anything unless they are a public building (like government buildings and libraries) but a store wouldn't seem to be a "public" building by the definition in the statue.
(b) A public building that has a metal detector at each public entrance or a sign posted at each public entrance indicating that no firearms are allowed in the building, unless the permittee is not prohibited from carrying a concealed firearm while he is on the premises of the public building pursuant to subsection 4.
4. The provisions of paragraph (b) of subsection 3 do not prohibit:
(a) A permittee who is a judge from carrying a concealed firearm in the courthouse or courtroom in which he presides or from authorizing a permittee to carry a concealed firearm while in the courtroom of the judge and while traveling to and from the courtroom of the judge.
(b) A permittee who is a prosecuting attorney of an agency or political subdivision of the United States or of this State from carrying a concealed firearm while he is on the premises of a public building.
(c) A permittee who is employed in the public building from carrying a concealed firearm while he is on the premises of the public building.
(d) A permittee from carrying a concealed firearm while he is on the premises of the public building if the permittee has received written permission from the person in control of the public building to carry a concealed firearm while the permittee is on the premises of the public building.
5. A person who violates subsection 2 or 3 is guilty of a misdemeanor.
6. As used in this section:
(a) “Child care facility” has the meaning ascribed to it in paragraph (a) of subsection 5 of NRS 202.265.
(b) “Public building” means any building or office space occupied by:
(1) Any component of the Nevada System of Higher Education and used for any purpose related to the System; or
(2) The Federal Government, the State of Nevada or any county, city, school district or other political subdivision of the State of Nevada and used for any public purpose.
Ê If only part of the building is occupied by an entity described in this subsection, the term means only that portion of the building which is so occupied.
(Added to NRS by 1995, 2725; A 1997, 63; 1999, 2767; 2007, 1914)