FIX: Material with import stackup file

src/pyedb/dotnet/edb_core/edb_data/simulation_configuration.py

@@ -2459,7 +2459,6 @@ def _read_cfg(self):  # pragma: no cover
         --------
 
         >>> from pyedb import Edb
-        >>> from dotnet.edb_core.edb_data.simulation_configuration import SimulationConfiguration
         >>> config_file = path_configuration_file
         >>> source_file = path_to_edb_folder
         >>> edb = Edb(source_file)
@@ -2478,7 +2477,7 @@ def _read_cfg(self):  # pragma: no cover
                 cfg_lines = cfg_file.read().split("\n")
                 for line in cfg_lines:
                     if line.strip() != "":
-                        if line.find("="):
+                        if line.find("=") > 0:
                             i, prop_value = line.strip().split("=")
                             value = prop_value.replace("'", "").strip()
                             if i.lower().startswith("generatesolderballs"):

src/pyedb/dotnet/edb_core/materials.py

@@ -212,10 +212,10 @@ def dc_conductivity(self):
     @dc_conductivity.setter
     def dc_conductivity(self, value: Union[int, float]):
         """Set material dielectric conductivity."""
-        if self.__dc_model:
+        if self.__dc_model and value:
             self.__dc_model.SetDCConductivity(value)
         else:
-            self.__edb.logger.error(f"DC conductivity cannot be updated in material without DC model.")
+            self.__edb.logger.error(f"DC conductivity cannot be updated in material without DC model or value {value}.")
 
     @property
     def dc_permittivity(self):
@@ -227,10 +227,12 @@ def dc_permittivity(self):
     @dc_permittivity.setter
     def dc_permittivity(self, value: Union[int, float]):
         """Set material dielectric relative permittivity"""
-        if self.__dc_model:
+        if self.__dc_model and value:
             self.__dc_model.SetDCRelativePermitivity(value)
         else:
-            self.__edb.logger.error(f"DC permittivity cannot be updated in material without DC model.")
+            self.__edb.logger.error(
+                f"DC permittivity cannot be updated in material without DC model or value {value}." f""
+            )
 
     @property
     def dielectric_model_frequency(self):