Basic Horror Movie Etiquette - Tumblr Posts

Tell me WHY, upon introducing a monster that melts in shadows, my players' immediate reaction was to leave the empty sunlit garden they were in to go inside, while splitting up? And why one of them had the idea to teleport right into the old, empty library with stained glass windows? I didn't mean to make that encounter scary, it was a single monster in the garden while they were together. Choices were made... Which altered the situation. I found it very funny though.