Why won't my dog clicker train?

Okay so I have a five year old chihuahua jack russel mix and I was wanting to introduce him to the clicker. I sat down with him for about thirty minutes and began the click and reward step. During this time he had no interest what so ever in the sound, nor did he relate it with the treat. He had all his focass on the hand with the treat. I tried clicking when he was looking away to see if he would respond but he didn't. I'm not sure how to go about this situation. Maybe because he is older he knows the treats are in my hand. Something like that. How do I get him to relate the sound with the reward. I can't click reward for hours, he can't have that many treats. Help please...