When a location is labeled as Ambiguous it means that there is likely another location with that same name in Tableau's geographic data. Therefore, more levels of detail are needed to give the exact location. By adding a Province column to your data, Tableau will recognize where to plot Suzhou and Wuxi. Hope this helps!
thanks, tracy, that could be the reason.
I already defined China for the map, as far as I know there is no other Suzhou or Wuxi city in China, also from drop down list, I couldn't find two suzhou. That's why I don't understand why should limit the province. could you help trace your geographic data, in China, there are two Suzhou or Wuxi in different province, and give me the province name?