Suppress blank fields in a sub report

[nbz24]

Hi everyone,
I have a data table which being displayed in a sub report.
The table contains 4 columns. My problem is, that I have blank fields on the first two columns. Currently, it looks like this:

----------------------------------------------------------------------------
<field1> <field2>

<field3> <field4>
----------------------------------------------------------------------------

I want it to look like this:

----------------------------------------------------------------------------
<field1> <field2> <field3> <field4>
----------------------------------------------------------------------------

So as you can see, I just want to make all columns appear in one row, regardless of any blank fields.

Many thanks in advance!