Pastel Still Life - Lemons

I have struggled with these lemons for weeks. The 'working sketch' was executed in an art class, it focuses on tone, light and shape in order to excite and amuse the eyes. I then moved to an acrylic, using the cketch as the base. The lemons rotted and were thrown away.

Perhaps this was the problem. My uncle, an artist, tells me I should not paint from photos. I should paint from real life. Photos deaden the subject, he tells me. It is painting for the sake of it, lacking in meaning, dull. He was disappointed by the 

No allowances for medium then... no oils with their interminable drying time. I struggled and struggled with the painting, with the result that my lemons look more like bombs. They lack the life and light of the original version.