Cannot insert a line between &1 &2 and &3; renumber to insert

What causes this issue?

You cannot insert a line between &V1& &V2& and &V3& because the
increment is lower than 1.

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?

Renumber the lines.
If you want to renumber service lines, choose <ZK>Edit</> ->
<ZK>Renumber</>.
If you want to renumber subitems, choose <ZK>Edit</> -> <ZK>Renumber
subitems</>.
Enter an increment value.
Enter the increment, for example, 10. The system replaces the existing
values in all the selected lines with the new values. In this example,
the system changes the line sequence 10, 20, 21, 30 to 10, 20, 30, 40.
If you have renumbered, select the line that is above where you want to
add the new one.
Choose <ZK>Edit</> -> <ZK>Insert Line</>.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.