Namespace '&1' is not a valid BW namespace

What causes this issue?

Namespace '&V1&' must be entered in both the BW table RSNSPACE and the
basic table TRSNSPACE or the view V_TRNSPACE. You also have to enter the
relevant generation namespace '&V2' in table TRNSPACE. THis value is
taken from table RSNSPACE.
Both namespaces must be set to 'Changeable' - providing they are not
empty.

System Response

You cannot edit or create an object in this namespace.

How to fix this error?

Use a different name.
Or contacct your system administrator. He/she can switch the namespaces
to 'Changeable' using transaction SE06, or - if they do not already
exist - enter them in the table named above using transaction SM30.
If the namespace '&V1' is empty, then the problem is with the generation
namespace '/BIC/'.

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

Error message extract from SAP system. Copyright SAP SE.