You see this error because you entered an entry without a date.
Causes
- In the entered transaction there are some amounts and some accounts, but there is no date in the Date column.
- In the File menu > File properties > Options tab, the Transaction date required option is activated (it is active by default), and it is therefore necessary for a date do be entered.
Solutions
- Enter a date in the transaction row
- Usually it is better for transactions to have a date. If however you wish to change this setting, you can do so, and the program will not require a mandatory date anymore.