strcmp() doesn't work with command line argument

i'm trying to pass arguments into main through the command line and then compare string in argv[1] with some strings in code. It doesn't work, always block else is executed even if i type exactly the same string! What's wrong?

    #include <iostream>
    #include <string.h>

    using namespace std;

    int main(int argc, char * argv[])
    {

    if (argc>2)
    {
        if (strcmp(argv[1], "ball ")==0)
        {...}
        else if (strcmp(argv[1], "dance ")==0)
        {...}

        else

         {
           cout<<"Ops"<<endl;
           cout<<argv[2]<<endl;
           cout<<argv[1]<<endl;
        }