Rolling a ladoo is the point at which a recipe reveals whether it worked. A mixture either binds under the palm or falls apart, and the failure has a small number of causes.
Fat is the primary binder
Most ladoos are held together by fat coating the particles, whether that is ghee in a flour-based mixture or the oil naturally present in ground nuts and coconut.
The fat has to be liquid at the moment of shaping. As it cools it solidifies, locking the particles in the position pressure put them in.
Which is why these mixtures are rolled warm rather than cold, and why a mixture left to cool fully has to be warmed again before it will shape.
Sugar contributes moisture as well as sweetness
Sugar dissolved in the mixture's residual moisture forms a syrup that acts as a second binder, gluing particles together as it sets.
Powdered sugar added to a dry mixture cannot do this, because there is no water available to dissolve it, so it stays as loose grains between particles.
Recipes using syrup rather than dry sugar are exploiting that, and they typically hold together more reliably at the cost of a slightly stickier finish.
Pressure has to be applied and then held
A ladoo is compressed, not merely rounded. The initial squeeze brings particles into contact so the fat and syrup can bridge them.
Rolling gently in an open palm never applies enough force, which is the most common reason a mixture that was fine in the bowl falls apart in the hand.
The traditional motion is a firm clasp followed by rotation, and it is the clasp rather than the rotation that does the binding work.
Particle size decides how much binder is needed
Fine flours have enormous surface area and need proportionally more fat to coat them, which is why those mixtures take more ghee than seems reasonable.
Coarse mixtures of chopped nuts or split legumes have less surface area but larger gaps, so they rely on syrup filling the spaces rather than on coating.
A mixture that crumbles despite adequate fat is usually too coarse for the binder it has, and grinding part of it finer fixes the problem faster than adding more ghee.
The rescue depends on which element is missing
A dry, dusty mixture needs warm ghee added a spoonful at a time until it clumps when squeezed. Adding a lot at once produces a greasy mass that will not hold either.
A mixture that is fatty but still crumbly needs moisture, and a small amount of warm milk or thin syrup usually brings it together.
A mixture that is sticky rather than crumbly has too much of both, and the fix is more of the dry base rather than refrigeration, which only postpones the problem.