I need help with my unknown lab for chemistry!!!?

i have narrowed the choices down to potassium phosphate, potassium dichromate, potassium chromate, and sodium iodide. The solution i received was clear. I did a cation ppt test and it didnt ppt with anything so i then did a flame test and the flame was bright orange (although i used a medal stick to put the chemical in) but when i held up the cobolt glass it was a bluish purplish flame. This has lead me to believe that it is either sodium or potassium. then i did an anion ppt test and it ppt with Cu, Pb, Hg, and Ag. I had then done a halogen test and the color was brownish with a dark pink ring at the top. My teacher told me it was not bromide and it clearly isnt Cl. I have no more of the solution to test so i have to go strictly off of these test results. Potassium Dichromate is supposedly an orange powder and since my aqeous solution was clear i doubt that is it but i hate to rule out something that could be right. IF you have any information on what it might be please help! My grade depends on me figuring out this solution.