In the Zen v.1.3.9h folder of templates / templates-default/buttons/english the button to add to cart is called "button_add_to_cart.gif"
I did as you suggested: created a button for tell a friend and it loaded and it shows up!!!!! see here: http://pregnantearth.com/NEW_ART_STORE/index.php?main_page=product_info&cPath=1&products_id=1
So this begs the question: do I have the correct file names?
Here is the php content of my button_names.php file - they all match the names of the images files in the templates-default/buttons/english folder
define('BUTTON_IMAGE_ADD_TO_CART', 'button_add_to_cart.gif');
define('BUTTON_IMAGE_ADD_ADDRESS', 'button_add_address.gif');
define('BUTTON_IMAGE_ADD_PRODUCTS_TO_CART','button_add_selected.gif');
define('BUTTON_IMAGE_BACK', 'button_back.gif');
define('BUTTON_IMAGE_BUY_NOW', 'button_buy_now.gif');
define('BUTTON_IMAGE_CANCEL', 'button_cancel.gif');
define('BUTTON_IMAGE_CHANGE_ADDRESS', 'button_change_address.gif');
define('BUTTON_IMAGE_CHECKOUT', 'button_checkout.gif');
define('BUTTON_IMAGE_CONFIRM_SEND', 'button_confirm_send.gif');
define('BUTTON_IMAGE_CONFIRM_ORDER', 'button_confirm_order.gif');
define('BUTTON_IMAGE_CONTINUE', 'button_continue.gif');
define('BUTTON_IMAGE_CONTINUE_SHOPPING', 'button_continue_shopping.gif');
define('BUTTON_IMAGE_DELETE', 'button_delete.gif');
define('BUTTON_IMAGE_DELETE_SMALL', 'button_delete_small.gif');
define('BUTTON_IMAGE_DOWNLOAD', 'button_download.gif');
define('BUTTON_IMAGE_EDIT_SMALL', 'small_edit.gif');
define('BUTTON_IMAGE_IN_CART', 'button_in_cart.gif');
define('BUTTON_IMAGE_LOGIN', 'button_login.gif');
define('BUTTON_IMAGE_NEXT', 'button_next.gif');
define('BUTTON_IMAGE_PREVIOUS', 'button_prev.gif');
define('BUTTON_IMAGE_REDEEM', 'button_redeem.gif');
define('BUTTON_IMAGE_RETURN_TO_PROD_LIST', 'button_return_to_product_list.gif');
define('BUTTON_IMAGE_REVIEWS', 'button_reviews.gif');
define('BUTTON_IMAGE_SEARCH', 'button_search.gif');
define('BUTTON_IMAGE_SEND', 'button_send.gif');
define('BUTTON_IMAGE_SEND_A_GIFT_CERT', 'button_send_a_gift_cert.gif');
define('BUTTON_IMAGE_SEND_ANOTHER', 'button_send_another.gif');
define('BUTTON_IMAGE_SHIPPING_ESTIMATOR', 'button_shipping_estimator.gif');
define('BUTTON_IMAGE_SOLD_OUT','button_sold_out.gif');
define('BUTTON_IMAGE_SOLD_OUT_SMALL','button_sold_out_sm.gif');
define('BUTTON_IMAGE_SUBMIT', 'button_submit.gif');
define('BUTTON_IMAGE_TELL_A_FRIEND', 'button_tell_a_friend.gif');
define('BUTTON_IMAGE_TELLAFRIEND', 'button_TellAFriend.gif');
define('BUTTON_IMAGE_UNSUBSCRIBE', 'button_unsubscribe.gif');
define('BUTTON_IMAGE_UPDATE', 'button_update.gif');
define('BUTTON_IMAGE_VIEW_SMALL', 'button_view.gif');
define('BUTTON_IMAGE_WRITE_REVIEW', 'button_write_review.gif');
define('BUTTON_IMAGE_READ_REVIEWS', 'button_read_reviews.gif');
define('BUTTON_IMAGE_GOTO_PROD_DETAILS', 'button_goto_prod_details.gif');
define('BUTTON_IMAGE_MORE_REVIEWS', 'button_more_reviews.gif');
define('BUTTON_IMAGE_CONTINUE_CHECKOUT', 'button_continue_checkout.gif');
??????
Thanks for your patience .... and assistance. It is not clear to me why this "tell a friend" button shows up and the "add cart" and "search" buttons don't (they're the two I've created created and am testing.)
Any enlightenment on this?