The emulator is often *not* an ARM device, but an x86 device (it's running
on your PC, after all).  Since you have a native code DLL, that's the most
likely cause of the problem.  You say that you were able to call it from an
eVC program.  Where was that program running?  If on the real device, you
have to use the same environment to test the managed code, to be sure that
you're doing the right thing.

Missing method exception also might indicate that you have not arranged to
export the function calls from your DLL in an unmangled format.  C++ mangled
exported function names to include information about the types of parameters
and return types (this is necessary because, in C++, you can overload a
function name with various versions distinguished by their parameter lists
and return types).  Since, typically, you are calling the functions from C#
as though they were plain C functions, no mangling is done to the
references.  If the functions are not declared with extern "C" in your C++
DLL, and are not listed in a DEF file for the DLL, that's a problem for you.

Paul T.