First, the post you revived is more than a year and a half old. Several aspects of Manager have changed since then.
So please describe exactly what you are trying to do if the answer below does not solve your problem. The topic subject you referenced was about reversing asset disposal. Your new topic is about selling an asset. You don’t do that with a sales invoice.
If you are selling a fixed asset, use
Receive Money in a cash or bank account. Allocate the receipt to
Fixed assets and the specific asset’s subacount. This will adjust book value for the asset. In the
Fixed Assets tab, edit the asset involved and tick the
Disposed fixed asset box, which will allow you to enter the disposal date.
If you are trying to use a sales invoice to bill the buyer of the asset, that is an incorrect approach, because your company is not generating revenue from services or inventory held for sale. You are, instead, selling an asset used for the production of income. The buyer is not acting as a customer in this case, even if they are in other cases. A bill of sale or payment receipt (which you can print after using Receive Money) is the appropriate documentation. For example, if a computer store owns the building where it operates and sells the building, the building buyer would not get a sales invoice the same way as someone who buys a laptop.