CREATE TABLE table_15748 ("Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Prod. code" FLOAT)

Who wrote the episode with a production code greater than 1.4 direcyed by rick wallace?
SELECT "Written by" FROM table_15748 WHERE "Prod. code" > '1.4' AND "Directed by" = 'rick wallace'
SELECT "Written by" FROM "table_15748" WHERE "Directed by" = 'rick wallace' AND "Prod. code" > '1.4'