Were you using tap water? Metal spoons or strainers? either could cause a problem.
This is my process to help you in the future:
1. remove liquid/ strain the grains - & enjoy
2. add grains, spring or distilled water & sugar to glass container
2b. optional additions: a slice of fresh ginger, a piece of dried unsulfered fruit, pinch of organic baking soda (most important to add some minerals if using distilled)
3. cover mouth of jar/container with paper towel & rubberband in place
4. sit on counter for 24-48 hours