QGIS » QGIS Application

I´m trying to set up a form value relation using a connection based on WFS.

The problem is that the filter expression for field “elementer” in layer “v_greg_flader” : current_value('hovedelement_kode') = "hovedelement_kode" doesn’t return any values to the drop-down widget although there is matching values for “hovedelement_kode” in layer “d_basis_hovedelementer” for all possible values of the same field in Layer “d_basis_elementer”

• All layers are based on WFS

• Layer “v_greg_flader” is the main layer, which contains (among others) the fields “hovedelement_kode” and “element_kode”
• Layer “d_basis_hovedelementer” contains lookup values for field “hovedelement_kode” in layer “v_greg_flader”

• Layer “d_basis_hovedelementer” contains lookup values for field “element_kode” in layer “v_greg_flader”

• There is a 1:n relation between “d_basis_hovedelementer” and “d_basis_elementer” on common field “hovedelement_kode”

Can you help look into this problem. Attached is a project illustrating the problem.
Regards
Lene