x11 forwarding does not work on my linux server

Hi I really want to run simple code on my linux server

and to forward plot result through x11 to my computer

This is my code....

#include <engine.h>
int main(){
    Engine *pEngine = engOpen("");
    engEvalString(pEngine, "plot([1:1:10],[1:1:10]), ");
    return 0;
}

But it doesn't work.

If I run directly run matlab and order plot (like "$matlab -nodesktop" and type "plot([1:1:10],[1:1:10])")

It works.

What is the problem?