Absolutely NOT a failure.
I do it all the time in my job - I try a new photographic technique or attempt something artistic that doesn't work. That doesn't make what I did a failure ... it means I learned something. I learned that *this* particular technique doesn't work for me. So now I have a learning opportunity - I look at myself and ask if I did it right. If I did, then I ask myself do I try to modify the technique or do I move on to something new?
Same with what you did - you tried something that didn't work the way you expected it to. So now you know. And now you move forward.
If we never tried anything new or different, we'd never grow.
Congrats on beating the guilt!