Issue API - How to Change Fitting Diameter

Hello,

I'm trying to create a code to change the size of the conduit and the fittings connected.

To change the size of the conduit is easy, this code do the job.

Parameter parameter = ele.get_Parameter(BuiltInParameter.RBS_CONDUIT_DIAMETER_PARAM);

The problem is on the fitting family, don't have any BuiltInParameter...

So I try to select the Connector and change the Radius value.

Kinda works but only with round values... When I try to apply a unround number I receive a ArgumentOutOfRangeException.

I'm using Revit 2018 and I don't if this ArgumentOutOfRangeException is a bug or has a better way to change Connector size.