this.items is not a function

[Brozerker]

I'm trying to use the paper-carousel like so:

<carousel-wrapper items-in-view="4" show-dots>
                <template is="dom-repeat" items="[[item.Charts]]">
                    <div class="chartIcon">
                        <chart-icon chart-type="[[item.ChartType]]" on-tap="_chartClicked"><chart-icon>
                    </div>
                </template>
          </carousel-wrapper>

custom-wrapper:

<paper-carousel items="[[itemsInView]]" responsive="600:2, 460:1" controls="true" dots="[[showDots]]" dotText="[[showDotText]]">
                <content></content>
            </paper-carousel>

when I load the page, I get this error:
Uncaught TypeError: this.items is not a function @ paper-carousel.html:13