I joined "1980" (Fields on foto) with ¨municipal¨ (the blue one graduate) through ¨CVEGEO¨ value. Then I tried to illustrate with graduate style the AUTO_PARTICULAR value.
Result: There is a clasification but not the illustration.
Before the aplication of graduate style, I had an another graduate style illustration of a value but of the same table of ¨municipal¨, that was good.
The problem is with the joined table. I recently imported through ¨Add Delimited Text Layer¨ with a .csvt file.