Unable to insert value to a newly created attribute , "Not editable. The attribute does not apply to this artifact"

What is proper way to create an attribute, to avoid error message- "Not editable. The attribute does not apply to this artifact" <o:p> </o:p>

I performed the following steps: <o:p> </o:p>

1.    Create an artifact, called “Import-Artifact”

System automatically created: ID and Contents <o:p> </o:p>

2.     Hight light Import-Artifact, from administration icon (top right),

Select Manage Project Properties  <o:p> </o:p>

3.    Select Tab Artifacts Attributes, then select New Attribute 

4.    Create attribute: Requirement ID, Rational 

5. Open the artifact “Import-Artifact” 

6. Inset column Requirement ID, Rational 

7.   Try to insert a value to Requirement ID, Rational

8.    Not editable. The attribute does not apply to this artifact"