The Difference Engine was built in the 90s.
Why has nobody succeeded in building the Analytical Engine?
Charles Babbage designed the Analytical Engine as a general-purpose computer to succeed his more limited difference engines. The Analytical Engine would be Turing complete and programmable in an assembler-like language (conditional branches and loops). Unfortunately, like the designs of his Difference Engine(s), it was not build in Charles Babbage's lifetime.
I am interested in reason for this.
Is the design incomplete? If so, what is missing?
The mill (CPU) itself should be impressive enough (as shown in the Wikipedia article)!