Number range interval 01 has not been assigned an internal number

What causes this issue?

Number range interval 01 in Number range NASTSORTNR has not been
assigned an internal number.

System Response

The required number cannot be taken from this number range.

How to fix this error?

Check Number range NASTSORTNR to see if Interval 01 has been set for
internal number assignment. If not, switch the appropriate setting from
'external' to 'internal'.
IF &DEVICE&='SCREEN'
<DS:TRAN.SNRO>Proceed</>
ENDIF

Error message extract from SAP system. Copyright SAP SE.