CREATE TABLE table_62993 ("Tie no" TEXT, "Home team" TEXT, "Score" TEXT, "Away team" TEXT, "Date" TEXT)

What is the Tie no of the Port Vale Away game?
SELECT "Tie no" FROM table_62993 WHERE "Away team" = 'port vale'
SELECT "Tie no" FROM "table_62993" WHERE "Away team" = 'port vale'