The parameter is read-only error


Here is what i want to do : among all the structural frames in my project, i want to detect if in their composition there is a specific material. For these material, i want to extract their specific volume and associate it to a parameter. Here is how i do that :

First of all, i’m sure i can do that easily :smiley:
Second of all, it doesn’t work, with a “the parameter is read-only” error in the last node.

Thank you for your help !

My first question would be “Can you modify that parameter through Revit natively?” Is the element inside a group or otherwise being controlled elsewhere and therefore dependent?

@martin.honet , hi

Are you realy store your ParameterValues in the correct Parameter?

ReadOnly means that in the Family, your parameter is driven by other parameters already like (a x b x c = m³)…


Thank you for your answers. In fact, the code seems to work even though i have this error message, which confuse me.