CREATE TABLE table_204_639 (id DECIMAL, "poll company" TEXT, "source" TEXT, "publication date" TEXT, "psuv" DECIMAL, "opposition" DECIMAL, "undecided" DECIMAL)

what was the next publication after the june 2010 publication of radio nacional de venezuela ?
SELECT "source" FROM table_204_639 WHERE id = (SELECT id FROM table_204_639 WHERE "publication date" = 'june 2010' AND "source" = 'radio nacional de venezuela') + 1
SELECT "source" FROM "table_204_639" WHERE "id" = (SELECT "id" FROM "table_204_639" WHERE "publication date" = 'june 2010' AND "source" = 'radio nacional de venezuela') + 1