Инжектор dll, не выполняется вызов MessageBox

#include <windows.h>
#include <TlHelp32.h>
#include <iostream>
using namespace std;
DWORD func(const char *ProcessName){
    DWORD ProcessId=0;
    PROCESSENTRY32 process;
    HANDLE Snapsot;
    Snapsot=CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS,0);
    process.dwSize = sizeof(PROCESSENTRY32);
    if(Process32First(Snapsot,&process)){
        while(Process32Next(Snapsot,&process)){
            if(!strcmp(process.szExeFile,ProcessName)){
                ProcessId=process.th32ProcessID;
                break;
            }
        }
    }
    CloseHandle(Snapsot);
    return ProcessId;
}
bool inject(DWORD ProcessId,const char *dllName){
    HANDLE process;
    LPVOID a;
    LPVOID b;
    DWORD c;
    process=OpenProcess(PROCESS_ALL_ACCESS,false,ProcessId);
    if(process==NULL)return false;
    a=(LPVOID)GetProcAddress(GetModuleHandle("kernel32.dll"),"LoadLibraryA");
    if(a=NULL)return false;
    b=(LPVOID)VirtualAllocEx(process,NULL,strlen(dllName),MEM_RESERVE|MEM_COMMIT,PAGE_READWRITE);
    WriteProcessMemory(process,b,dllName,strlen(dllName),NULL);
    CreateRemoteThread(process,NULL,c,(LPTHREAD_START_ROUTINE)a,b,c,NULL);
    CloseHandle(process);
    return true;
}
int main(){
    cout<<inject(func("CrackMe.exe"),"dll.dll");
    system("pause");
}

#include<windows.h>
#define DllExport extern"C" __declspec(dllexport)
DWORD APIENTRY DllMain(HMODULE hinstDLL,DWORD fdwReason,LPVOID lpvReserved){
    switch (fdwReason){
        case DLL_PROCESS_ATTACH:{
            MessageBox(NULL, "Inject!", "Inject!", MB_ICONERROR);
            break;
            }
    }
    return true;
}