Host Parameter in Duct accessories Schedule

I want to know where i make mistake in Dynamo.
I want duct accessories schedule Floor by Floor.

Does the “host” parameter give you actual Level elements? or just a list of string of Level Names?
It usually returns string, and strings do not have Name because they are not Revit elements.

Simply feed the output of GetParameterValuebyName to SetParameterValueByName.

Or instead of Host, use “Level” Parameter if available in the family.

“Level” parameter are available in family. when i use “Level” also give same problem.

The issue could be the null value…
I would suggest filtering out the elements that return null in their name…
see the attached fileTestFiltered.dyn (7.2 KB)

showing same problem.

Try this out
download clock work package and use List.ReplaceNull