dlopen failed to load library from unprivileged user

I load a native library from C# code through dlopen function.

[DllImport("libdl.so")]
public static exte IntPtr dlopen(string filename, int flags);

const int RTLD_NOW = 2; // for dlopen's flags 

// call
IntPtr r = dlopen(libFileName, RTLD_NOW);

If I run application with sudo, library is load.
If I run application from unprivileged user, I have a error.

Output command lld for library

linux-vdso.so.1 =>  (0x00007ffd51fe2000)
 libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f6e472ff000)
 /lib64/ld-linux-x86-64.so.2 (0x000055f33e18f000)

My system is Kubuntu 1504

Help me. Any idea?