[CppAD] newbie - help: Assertion `Taylor[depvar[i]] == z[i].value' failed

[Marco Morandini]

I'm a new user, and I'm trying to use
CppAD within a scientific simulation code.
The idea is to compute the Jacobian matrix of
some experimental complex joint elements without the need
to code them explicitly.

Currently I'm stuck with this run-time error (cppad-05-11-28):

  error from an unknown source:

mbdyn: ../../libraries/libcppad/CppAD/local/Fun.h:491: 
CppAD::ADFun<Base>::ADFun(const VectorADBase&, const VectorADBase&) 
[with VectorADBase = std::vector<CppAD::AD<double>, 
std::allocator<CppAD::AD<double> > >, Base = double]: Assertion 
`Taylor[depvar[i]] == z[i].value' failed.
Aborted

that is triggered by ADFun:

	CppAD::ADFun<doublereal> f(x_indep, y_dep);

The code base is huge, and I don't even know if I'm
using CppAD in a wrong way (probable)
or I'm facing a bug of the library.
The code is Mbdyn, an open source multibody code  (www.mbdyn.org)
Could you suggest a way to track down the problem?

Thanks in advance,

Marco Morandini