strcmp in C++ not working

Question

Why does the strcmp() function not work in the following code excerpt?: (The program reads data from another file)

#include <iostream>
#include <fstream>
#include <cstring>
#include <iomanip>

using namespace std;

struct schokolade
{
    char name[20];
    int gewicht;
    int zutat_id[5];
    int menge_in_prozent[5];
};

struct zutat
{
    char name[20];
    float preis_pro_100gramm;
};


int main()
{
    char data[20];
    schokolade schokosorten[3];
    zutat zutaten[7];

    ifstream fin;
    fin.open("schoki.txt");
    //Check for error:
    if(fin.fail()){
        cout << "Datei schoki.txt konnte nicht geöffnet werden." << endl;
        return 0;
    }

    int anzahl;
    char name_zutat[20];
    int anteil;

    while(fin.getline(data,20)){

        if(strcmp(data, "vollmilch_mandel")==0){ //DOES NOT WORK!
            strcpy(schokosorten[0].name, data); 
            ...

The code continues after this but it's not interesting for this question.