Hi Casinotime,
Hope you’re having a good week! 
You’re not alone with this, there was some great advice on GPWA recently on this topic: http://www.gpwa.org/forum/help-traffic-but-no-conversions-175345.html. The general consensus was that the key to convert is to ensure that you have placed banners in highly visible spots on your webpage.
I work with JuegaTuSuerte and they require new players to deposit before they earn a bonus, which can work well in converting players who wouldn’t otherwise deposit.
Are you concentrating on casinos or do you promote a variety of games to the Spanish market?