CREATE TABLE table_28544 ("Round" TEXT, "Circuit" TEXT, "Date" TEXT, "Pole Position" TEXT, "Fastest Lap" TEXT, "Winning Driver" TEXT, "Winning Team" TEXT)

On what date is the winning team Abt Sportsline and pole position Mattias Ekstr m in the Circuit Ricardo Tormo , Valencia?
SELECT "Date" FROM table_28544 WHERE "Winning Team" = 'Abt Sportsline' AND "Pole Position" = 'Mattias Ekström' AND "Circuit" = 'Circuit Ricardo Tormo , Valencia'
SELECT "Date" FROM "table_28544" WHERE "Circuit" = 'Circuit Ricardo Tormo , Valencia' AND "Pole Position" = 'Mattias Ekström' AND "Winning Team" = 'Abt Sportsline'