PlotXY: getting an error

I'm trying to PlotXY in CVI. I have a graph on the second tab page of my panel, the graph have constant name "GRAPH_SPECTRUM". Here is the test code:

int plotHandle;
double x[100], y[100];

for (i = 0; i < 100; i++)
{

x[i] = 1.00 * i;
y[i] = 0.1 * i * i;            // let's try a simple parabola

}

GetPanelHandleFromTabPage (panelHandle, PANEL_TAB, PAGE_TWO, &Tab2PanelHandle);

plotHandle = PlotXY (Tab2PanelHandle, TABPANEL_2_GRAPH_SPECTRUM, x, y, 100, VAL_DOUBLE, VAL_DOUBLE, VAL_FAT_LINE, VAL_EMPTY_SQUARE, VAL_SOLID, 1, VAL_RED);

I'm getting an error "Function PlotXY: The control is not the type expected by the function"

Could anyone help please?