I do good ol' ta and titi because they are standard syllables for teaching elementary rhythms, and it's convenient to make the sounds the same across the board and from school to school. My theory is that you gave them too much info at once- at least, did you all that you said above in one session? I would introduce ta and titi in the third or a later session, once I was sure they had the concept first steady beat, and then of long and short sounds. I often introduce the symbols, an upright stroke for ta and 2 strokes connected by a beam for titi, before I give them names, and use them with the animal or food names, as a visual recognition. Soon they begin to get it that the one that stands alone is a longer sound, the "steady beat" sound, and the "monkey bars" are shorter sounds. Then I give them names, and we chant the names and clap, or just chant, always in the context of words of a rhyme, such as
"Apple peach, pears and plums
Tell me when your birthday comes"

It takes time for young children to learn the sounds and symbols- think of the years it takes them to learn to read letters and words and sentences and paragraphs!