Why is there not a plaque in Venice in honour of Henry James?

Plaque to Tchaikovsky, Riva degli Schiavoni, Venice
On the Riva degli Schiavoni, a short distance from each other, stand two hotels, the Londra Palace and the Pensione Wildner.

In the winter of 1877, the Russian composer, Peter Tchaikovsky, spent two weeks in the Londra Palace, where he worked on his fourth symphony. The event is duly commemorated by a grand plaque. Four years later, in the spring of 1881, the American writer, Henry James, spent three months in the Pensione Wildner, where he completed his novel The Portrait of a Lady. However, in this case the wall of the pensione is bare. 
The garden of the Palazzo Soranzo Cappello, Venice
Between 1869 and 1907, Henry James visited Venice (for longer or shorter periods) a total of ten times. He set one of his most famous novellas, The Aspern Papers, in Venice. The Palazzo Soranzo Cappello (and its garden), which is situated on the Rio Marin, served as the model for the palace where much of the action of the novella takes place. James finished The Aspern Papers during one of his many sojourns at the Palazzo Barbaro, the property of his Bostonian friends, Daniel and Ariana Curtis. He later used the palace as the model for the Palazzo Leporello, which Milly Theale rents in his novel The Wings of the Dove

And yet neither the Palazzo Soranzo Cappello nor the Palazzo Barbaro is graced with a plaque!