orderBy itemtype properties with pagination

Hello community,

I am facing a new challenge, I need to sort the answer of a SOAP request but since I have an itemtype property, I only figure to sort on the id of the itemtype used in the property and not on the name of the instances...

Datamodel :

- I have an item bug

- this item has a property "criticality" that is an itemtype property linked to 4 items with a property _name and values K1,K2,K3 and K4

I would like to get a page of the first 100 issues over all sorted by ascending criticality thus K1,K2,K3,K4...


<Item type='bug' select='_criticality' action='get' page='1' pagesize='25' orderBy='_criticality'>
</Item>

With that request I get a set of issues but sorted with the order K3 K1 K4 K2 since it's using the id of the property itemtype _criticality... 

I tried to orderBy _criticality._name and other stuff but it's not sorting at all...

Thanks in advance,

Hadrien