Work cited

After class I was still a little confused about the work sited exercise. In the exercise when we did the work sited for the poem. Why was it not correct to put the title of the poem as a subtitle?

WORK CITED

Today's class sure did help me with the way we need to work cite. It is important to document all the important information.
The last work cited we did, I had some problems with. Now that I see the answer, I reread the problem and now see how it had all the information in it.