“A Country Practice,” one of Australia’s most successful and long-running drama series, has been canceled after 12 years on the Seven Network.It will conclude with a two-hour episode in November. The Seven Network and producer JNP Films said it had been “decided to finish production … later this year.” No reason was given. Ratings have been good, but the format was aging, observers note. JNP is developing a spinoff series for 1994 set in the same fictional town, Wandin Valley. “A Country Practice,” which centers on the lives of folks in Wandin Valley, has been a consistent and durable rater for Seven and sold to dozens of countries.