DGET with discontinuous range

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Suppose this is sheet 1, the database we want to work on :

        A       B              C                      D                             E       F        G      H         I         J           K          L        
 1   | ID  | Création | Modification | Tache                                  | Début    | Fin | Délais | Durée | Urgence | Importance | Etat    | Résolution |
 2   |  1  | 12/02/14 | 12/02/14     | Installer Debian sur serveur radionet  | 12/02/14 |     |        |       | neutre  | neutre     | Fait    | adopté     |
 3   |  2  | 12/02/14 | 12/02/14     | Installer bind sur serveur radionet    |          |     |        |       | neutre  | neutre     | Fait    | adopté     |
 4   |  3  | 12/02/14 | 12/02/14     | Configurer bind sur serveur radionet   |          |     |        |       | neutre  | neutre     | nouveau |            |
 5   |  4  | 12/02/14 | 12/02/14     | Configurer réseau sur serveur radionet |          |     |        |       | neutre  | neutre     | nouveau |            |
 6   |  5  | 12/02/14 | 12/02/14     | Sécuriser serveur radionet             |          |     |        |       | neutre  | neutre     | nouveau |            |

And this is sheet 2, where we query the database.

           A          B         C                                                 D                    E             F             
 1   | Evénement   | ID | Tâche                                  |                                 | Date     | Commentaire |
 2   | Commencment |  4 | Configurer réseau sur serveur radionet |                                 | 12/02/14 |             |
 3   |             |  2 | Err:509                                | =DGET($A$2:$D$7"Tache",B14,B16) |          |             |

I want to enter a formula in the C column such that it gets its value from the E column of sheet 1, where sheet 2 B column (ID) matches sheet 1 A column (ID).

I tried to enter this as a formula in sheet 2 $C$2 cell:

=DGET($A$2:$D$7,"Tache",B14:B15)

And it works fine for this cell because the SearchCriteria B14:B15 is a range. But for the sheet 2 $C$3 cell :

=DGET($A$2:$D$7,"Tache",B14:B16)

Gives a 502 error : function argument isn’t valid.

What formula would I have to use ?

You can download the example file here : http://www.datafilehost.com/d/f623fd5a

Answered on libreoffice forums : the solution was to use OFFSET (or VLOOKUP).