To chain a parameter to another parameter you have to include it in one of that parameters action.
Sequence
Create two parameters. P1 is the control parameter, P2 the one that will be changed. Remove all action grips from P2
Create an action for parameter P1 and include P2 in the selection set of objects. In the case of your block I included the end of the paramjeter that will move, using a crossing as the action was a stretch.
Create an action for P2 selecting the gripless parameter end that will move and select the objects, then constrain the objects.
Right click on the parameter to be chained and select Properties. At the bottom under Misc the Chain Actions can now be set to Yes. Click on the action then right click and select properties.
Under Overrides you can set the Distance Multiplier. The Angle Offset is relative to the parameter direction.
You really need to play about with it to fully understand what does what. It took me months, on and off, whilst playing with an advanced dynamic door block to finally get some of this.