What's the number of the episode seen by 2.99 millions of people in the US, where performer 2 was Heather Anne Campbell?
CREATE TABLE "table1_23294081_11" (
  "no" real,
  "num" real,
  "original_airdate" text,
  "performer_1" text,
  "performer_2" text,
  "performer_3" text,
  "performer_4" text,
  "u_s_viewers_millions" text
);
SELECT MIN("num") FROM "table1_23294081_11" WHERE "performer_2"='Heather Anne Campbell' AND "u_s_viewers_millions"='2.99';