Function is not defined

The function is not defined when I try to call it. Please help.

		<?php 
		$terms = get_terms(
			array(
				'taxonomy' => 'product_categories',
				'hide_empty' => false
			)
		);

		echo '<pre>';
		print_r($terms);

		$i = 0;

		foreach($terms as $term) {

			if($i=0)
			{
			?>

				<div class="product-categories left">

					<div class="category-image">

						<?php
						if (function_exists('get_wp_term_image'))
						{
						    $meta_image = get_wp_term_image($term->term_id); 
						}
						?>

						<?php echo $meta_image; ?>	

					</div>

					<div class="category-text">

						<?php echo $term->description; ?>

					</div>

				</div>

			<?php
			} else {
			?>

				<div class="product-categories right">

					<div class="category-image">

						<?php
						if (function_exists('get_wp_term_image'))
						{
						    $meta_image = get_wp_term_image($term->term_id); 
						}
						?>

						<?php echo $meta_image; ?>	

					</div>

					<div class="category-text">

						<?php echo $term->description; ?>

					</div>

				</div>

			<?php
			}

			echo $term->term_id;

		}
		?>