JavaFX 2.0 :: File Browser - Adding Node To FlowPane Or TilePane

I trying to make a file browser but when i try to add item to a FlowPane through  me an error at runtime, look at this code if i add label with imageView when there are more than x ítem the error appear.

package first.sample; 
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.image.ImageView;
import javafx.scene.layout.FlowPane;
import javafx.stage.Stage;
 
[Code] .....

But if i add the label and the imageView alone the error didn't show. Ihave folder in my pc with more than 1200 file and the error always appear. Is there a way to make a flowpane or tilepane hold enough items?