As you can see in the below picture.
The pump you chose is the pump of blue bottle (on the left),
the bottle you chose is on the right.
The connecting part between pump and bottle (spiral part),
bottle on the right has a shorter one,
so the pump could not firmly connect to the bottle.
We asked the supplier to find a 50ml bottle for the pump of blue bottle.
Will keep you informed if we find something. ><