Get a bottle of Loctite Super Glue Precision, it has a fine nozzle for getting into fine cracks and is of a thinner consistancy.
Try seeing if you can get a few drops into the crack, if it seems to sink in after more than a few drops, chances are that the glue is penetrating into a wood crack, as this will soak up the glue. If it is a lacquer crack (which I doubt), it will collect on the surface after a few drops, after it has finished running behind any lacquer that has lifted away from the wood.
If it is a wood crack, the glue will strengthen it and any excess can be sanded and polished flat.