What does the “not found” in this case mean ?
This usually means that the executable cannot find one or more (shared) libraries to satisfy its external symbols.
This usually happens when no libraries are stored in the initramfs, or there is a shared library missing that the executable needs.
This can also happen if the executable is built with a C library that is incompatible with the runtime library, e.g. uClibc versus glibc/eglibc.
strings executable | less is the quickest way to see the required libraries and external symbols that the executable requires.
Or
Recompile your program and use static linking by specifying the -static option.