How to differentiate Zn 2+ and Al 3+ on the result of blue lake test

While performing test for basic radical in analyzing a salt qualitatively. I found out that the salt gave the blue lake test and since we were taught that only Al 3+ gives blue lake test, I thought it was Aluminium ion and wrote it the same. Later, my teacher told me I was wrong and it was Zinc ion. But then how did it give the blue lake test. How do I tell if the ion is Zinc or Aluminium? 


If I could check the ion by any other reagent?


