FitNesse - Click on Image

I am trying to click on an image. I circled it in red in the following screenshot:

I am trying to click the blue cross. 

I've tried the following methods:

| verify link | LINK_TEXT or LINK_TEXT[INDEX] | URL contains | URL_TEXT |

| click on link | LINK_NAME or LINK_NAME[INDEX] |

| click on button | BUTTON_NAME or BUTTON_NAME[INDEX] |

The code in the interface has the following general structure:

a!imageField(
    .
    .
    .
    label: "View",
    images: a!documentImage(
        .
        .
        .
        caption: "Add a New Route",
        link: a!dynamicLink(
            label: "+ Add New Route",
            .
            .
            .
        )
    )

)