Why does ADOX GetPermissions return 0 for an Access Form with Open/Run group permission set?

Question

Here's the scenario:

1. I have an Access 2003 (.MDB) database with User Level Security
2. I have a group G and a form F
3. Through "User and Group Permissions" dialog box, I explicitely set Open/Run permission (and only that) for group G on form F
4. I log in as user U (a member of group G) and can open the form F
5. In VBA I set an ADOX.Catalog variable cat to the current database and expect that the following call return something like adRightExecute (i.e.: 0x20000000); but it returns 0 (the last parameter is the GUID that designates Forms): cat.Groups("G").GetPermissions("F", adPermObjProviderSpecific, "{c49c842e-9dcb-11d1-9f0a-00c04fc2c2e0}")

I googled the issue in whatever creative search method I knew and was surprised that this case has not been addressed during the two decades that ADO is around!... So probably I am doing something wrong.

I would greatly appreciate if anyone could give me a hint.

UPDATE:

• Having the following situation:

• And the following function:

Function GetPermissionsGroupForm(groupName As String, formName As String) As Long

    Dim cat As ADOX.Catalog
    
    Set cat = New ADOX.Catalog
    Set cat.ActiveConnection = CurrentProject.Connection
    GetPermissionsGroupForm = _
        cat.Groups(groupName).GetPermissions( _
            formName, _
            adPermObjProviderSpecific, _
            "{c49c842e-9dcb-11d1-9f0a-00c04fc2c2e0}")

End Function

• GetPermissionsGroupForm("G", "F") returns 0 (equally with ADOX 2.8 and 6.0)

UPDATE 2:

For information, the structure of ADOX Permissions (Long) is:

BIT	Value	Meaning
00	0x00000001	NOT USED
01	0x00000002	NOT USED
02	0x00000004	NOT USED
03	0x00000008	NOT USED
04	0x00000010	NOT USED
05	0x00000020	NOT USED
06	0x00000040	NOT USED
07	0x00000080	NOT USED
08	0x00000100	adRightDrop
09	0x00000200	adRightExclusive
10	0x00000400	adRightReadDesign
11	0x00000800	adRightWriteDesign
12	0x00001000	adRightWithGrant
13	0x00002000	adRightReference
14	0x00004000	adRightCreate
15	0x00008000	adRightInsert
16	0x00010000	adRightDelete
17	0x00020000	adRightReadPermissions
18	0x00040000	adRightWritePermissions
19	0x00080000	adRightWriteOwner
20	0x00100000	NOT USED
21	0x00200000	NOT USED
22	0x00400000	NOT USED
23	0x00800000	NOT USED
24	0x01000000	NOT USED
25	0x02000000	adRightMaximumAllowed
26	0x04000000	NOT USED
27	0x08000000	NOT USED
28	0x10000000	adRightFull
29	0x20000000	adRightExecute
30	0x40000000	adRightUpdate
31	0x80000000	adRightRead

I desperately tried all NOT USED bits and some combinations of the defined ones in order to set the Open/Run permission through SetPermissions ... No success!