Check your web server's error log; I bet that XML::Parser isn't loading properly, and that failure is producing the 502 message you see.

More generally, I suspect that your compilation host doesn't really have "the same environment" as the embedded Linux box. Just having another machine running Linux is not enough; it needs to be truly compatible at the hardware and library level. See Roger's comments below about cross-compilation techniques, or contact your embedded systems vendor for more information.