The wrong signature

Auctioneer Notarishuis Arnhem B.V. sold this painting in 2001:

River 32 x 46 cm Signed bottom-right.

This is not a real Zandleven.
We have two strong arguments for this: the signature and the technique.

Signature. A good example of Zandleven's signature is:

If we compare this with the signature of the River-painting:

then we immediately observe the difference in te shape of the second letter, the A. Zandleven never wrote that a in the form of a conical cap.

Also the used technique is not Zandleven's style. He didn't paint clouds so often, and when, they are generally rather vague. Example: a detail of JAZ-1914-027:

When Zandleven painted recognizable clouds, he made them expressionistic, a bit van Gogh-style, like in this detail of JAZ-0000-001:

and for sure not this way: