How to make header of matrix tablix fixed when the xml dataset tied to the Matrix tablix doesnt have value

I have a xml in usual form which has following structure

<test> 

<element></element>

</test>

But sometimes I get no element under the test xml tag like shown below

<test></test>

Which causes my tablix to drop the tablix header as well as the tablix from the report.

I basically want the matrix tablix to stay with header but with blank value as shown in the diagram above.

Does anyone know how can we make this fixed?

=IIF(Fields!test.Value="",TRUE,false) on row visibilty but its not working.