Why can't I merge pandas dataframes

[learnpython2018]

I'm just trying to learn python and started with the imdb database files. (the headers and the data files can be seen here: https://www.imdb.com/interfaces/)

When I try to merge the two different data frames. I keep getting the error key not found:

ratings = pd.read_csv('title.ratings.tsv', sep = '\t').drop_duplicates(subset = 'tconst', keep = 'first')
titles = pd.read_csv('title.akas.tsv', sep = '\t').drop_duplicates(subset = 'titleId', keep = 'first')
titles.merge(titles, ratings, left_on="titleId", right_on="tconst")

I can't figure out what I'm doing wrong. Any guidance would be appreciated.