Watercolor painting - Antonio Rotta? and Value

Dear members,
I have a very old watercolor painting I guess is Antonio Rotta.
An expert told me it is an old original painting but he couldn't certify the artist.
Can you tell me where can I try to find more or a certification?
Of course, what is the value for this nice painting?
Thank you.

 

I'm afraid I'm not much help... Antonio was indeed a fine artist in the late 1800s, but I am most familiar with his oils, which produced a much more realistic, refined look. And in the examples I find, he signs with his whole name. A look at the back of the painting would be helpful...

Whatever the case... it's very pretty.

 

Thank you for the help.
I am comparing it to this one, similar from same artist.

http://www.invaluable.com/auction-l...903-a-boy-playing-the-flute,-637-c-6k5snileaa

 

That does look similar!
I'm still confused about the signatures... but I may be getting hung up on a detail.
Good luck with it!