Joining more than two tables is the same as with two tables so you need to have some mistake in the table names, column names or syntax.
Typically the tables are listed in the ON clause in the same order as they are in the FROM clause. Also I don't see any need for the parenthesis.
So simply try something like
SELECT Sector.SectorName, Association.AssociationName, Company.CompanyName, Company.CompanyLocation,Product.ProductDesc,Product.RawMatDesc
FROM Sector
INNER JOIN Association ON Sector.SectorID=Association.SectorID
INNER JOIN Company ON Association.AssociationID = Company.AssociationID
INNER JOIN Product ON Company.CompanyID = Product.CompanyID