ios4 sdk, uiwebview with custom button on it

I'm using iPhone OS 4 and creating an application. I've a webview, over which I'm placing two custom buttons with images (no text). When I'm running the app, I'm not seeing the buttons at all.

any suggestions?

I've a tab bar view and one of the view has this web view.

Edit: You can download the XIB and related files from http://dl.dropbox.com/u/945659/zip.zip When I'm calling this xib as "presentModalViewController", i'm seeing the buttons. But when I'm add开发者_开发问答ing this as one of the views in tabbarview, i'm not seeing the buttons at all. I didn't place the png files related to buttons. But I'm seeing the buttons when I'm using custom button with text only (label). The same button is not seen when I'm using "image". I'm setting the image in XIB itself.

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I found the issue. I didn't add the resources to target.