I think the issue is digital/analog. Just one question. are you using the micro-sequencer bit, the one with the four dimmer, or the sequencer bit, the one with the eight outputs?
A look into the schematics of the latch bit sometimes helps.
The latch is a pure digital circuit. It has a schmitt-trigger input buffer and the clocked D-flipflop. It will only work, if the input signal has a certain level and also clearly returns to "low" which is about 0V.
The bits from the synth kit are basically analog bits. They output and accept analog signals in the range from 0V to about 5V.
By default the power bit has a "high", 5V output on the signal pin. Therefore it is no surprise that the first combination, [power] - [button] - [latch] - [oscillator], works.
The keyboard bit is designed to output analog values equivalent to certain notes. It might not reach appropriate levels to fullfill the requirements of the latch bit. However, I assume there should be some combinations that will work.
Hope this points you into the right direction.