CSV Parsing Function not recognizing Empty Values

I have a CSV with 7 Fields

me,val1,val2,val3,val4,val5,val6,
me,val1,val2,val3,val4,val5,val6,

Im parsing this using the following function

void readcsv()
{

    lk_dispclr();
    lk_disptext(2,0,"Parsing CSV..",0);
    lk_disptext(3,0,"Please Wait..",0);

    FILE* stream = fopen("input.csv", "r");
    if(stream!=NULL)
    {
    char line[1024];
    while (fgets(line, 1024, stream))
    {

    char *tmp = strdup(line);      
    char a1[20]= "";
    char b1[20]= "";
    char c1[20]= "";
    char d1[20]= "";
    char e1[20]= "";
    char f1[20]= ""; 
    char g1[20]= ""; 
    strcat(a1, getcsvfield(tmp, 1));
    strcat(b1, getcsvfield(tmp, 2));
    strcat(c1, getcsvfield(tmp, 3));
    strcat(d1, getcsvfield(tmp, 4));
    strcat(e1, getcsvfield(tmp, 5));
    strcat(f1, getcsvfield(tmp, 6));
    strcat(g1, getcsvfield(tmp, 7));

        //printf("Field 1 would be %s\n", a1);
        // printf("Field 2 would be %s\n", getcsvfield(tmp, 2));
        // printf("Field 2 would be %s\n", getcsvfield(tmp, 3));
        // printf("Field 2 would be %s\n", getcsvfield(tmp, 4));
        // printf("Field 2 would be %s\n", getcsvfield(tmp, 5));
        // printf("Field 2 would be %s\n", getcsvfield(tmp, 6));
        execute("INSERT INTO sdata  (uid,sid,name,area,type,stbamount,pkgamount) VALUES('%s','%s','%s','%s','%s','%s','%s');",a1,b1,c1,d1,e1,f1,g1);
        // NOTE strtok clobbers tmp
        free(tmp);
    }
 lk_dispclr();
 lk_disptext(2,4,"CSV Imported!",1);
 lk_getkey();
}
else
{
lk_dispclr();
lk_disptext(2,4,"CSV Not Found!",1);
lk_getkey();

}



}
//Used for parsing CSV
const char* getcsvfield(char* line, int num)
{

    char buffer[1024]= {0};
    strcpy(buffer,line);
    const char* tok;
    for (tok = strtok(buffer, ",");
            tok && *tok;
            tok = strtok(NULL, ",\n"))
    {
        if (!--num)
            return tok;
    }
    return NULL;
}

But if the 6th field (val5) is missing val6 is getting inserted in the Table at the position for val5, where it actually should be blank.

What im i doing wrong?