Item quantity less than or same as quantity of all account assignments

What causes this issue?

You have already distributed the requested quantity of this material
among the account assignment items. If you create a further asset and
assign a quantity to it, you will exceed the required quantity.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Check the quantities of the individual account assignment items.

Error message extract from SAP system. Copyright SAP SE.