According to Google, there is a business called 'Total Wine & More' with the address of 6671 S Virginia St located in this building:
I zoomed way in to specify the building, but if you'll zoom out you'll notice it's much closer to the ramp than it is to S Virginia St.
[b]So step 1[/b], click S Virginia St and add a house number for this building for 6671 (you'll have to put it in the middle of the parking lot sort of near the 6675 number since the maxium distance doesn't reach) and put the stop point at the entrance to the parking lot (near Sierra Center Parkway.)
[b]Step 2[/b], add some parking lot roads (just the border and 'main lanes' of the parking lot should be sufficient, it's currently not standard to map every lane of a parking lot), making sure to include the drivable surfaces that are nearest any businesses and anywhere the parking lot connects to the surrounding streets.
[b]What the user will see after the fix[/b]: Waze will route him onto S Virginia St and then into the parking lot, directly taking him to the front door of the business. Note that it will only route the user on the parking lot roads you map, so if you only map the border, it will suggest that they not drive through the parking lot but instead travel around the border of it. (However, this is generally 'close enough' that the user can figure out where to go from there.) On the flip side, every parking lot road you add on the map will be permanently displayed for all users, for a slight additional amount of clutter (including users who are just driving past and not navigating within this parking lot) so until Waze changes how parking lot roads are displayed the current standard is to not map unnecessary lanes.
[b]Reason this happens[/b]: Google has coordinates for 'just the address' and it has coordinates for the address by POI or business name (and possibly multiple POI's for multiple business names all sharing the same address). It's silly that it does this, but it can result in a different location for the POI than for the address with no business name specified, even though it's the same address. In this case, the POI for the business is closer to the ramp than it is to any other drivable surface currently mapped by Waze, including S Virginia St.
[b]Possible complication[/b]: If the POI in google is slightly off from the building and/or even a correctly mapped parking lot road in the front of the building is still not 'close enough' to the location provided by Google that Waze is still mapping to the drivable surface behind the address, usually/sometimes adding the house number in Waze will fix that too but your best bet is to go into Google.com/mapmaker and submit a request to move the POI closer to the front of the building. At that time you may also want to move the 'pin' for the 'address without a business name' to the correct location as well.
I checked this specific location and the pin with the business name is sort of in the middle of the building but should be close enough if you add a parking lot road in front of it, that should be closer than the ramp behind it without an edit necessary in Google. The pin for the address without a name is smack in the middle of the street a little north of the actual parking lot the businesses are in, exactly where it shows when searching that address in Waze. I'd go ahead and make the edits in Google for you but they're currently in maintenance.
[b]Variation[/b]: Sometimes the POI information comes from a Landmark in Waze (normally not for simple businesses like this since they shouldn't be mapped, but for parks and airports and stuff.) If this POI provided by Waze is again closer to the 'wrong' drivable surface than the correct one, the same kind of thing can happen. The POI for the landmark can be easily seen as the 'dot' in the middle that you use to move the entire landmark without changing the shape of it (after selecting it of course.) The workaround for this is to leave the 'main' landmark with the correct shape, but no name, and create a tiny landmark near the entrance of the location that has the name. This POI dot is also where the name shows up in the Waze client as well (if/when the user is at the correct zoom/angle to see the name come up at all.)
[b]In the future[/b]: Make sure you also ask the user what, if any, business name they used to search with, as that will let you know which location Google is giving them. You can also attempt to find this 'business name' yourself, like I did, based on the address alone, but getting that data from the user is more accurate as there could be multiple business listings in Google sharing the same address but for whatever reason not all located in the same place. (In which case I recommend 'report duplicate' in Google's mapmaker or at the very least repositioning the offending data.)