Magento product image import not assigning image to product
http://magento.stackexchange.com/questions/18981/how-to-import-product-images-from-csv
http://stackoverflow.com/questions/11684326/magento-1-7-product-image-import-not-assigning-image-to-product
It seems your problem occurring because of image positioning.
sku, image, small_image, thumbnail, _media_image, _media_attribute_id, _media_position, _media_is_disabled
123, /Agent700.jpg, /Agent700.jpg, /Agent700.jpg, /Agent700.jpg, 88, 1, 0
Make your CSV as per the above norms and change the column as per your requirement but do not change 88 which is _media_attribute_id. and keep 1,0 for _media_position & _media_is_disabled.