If you are unable to load the user-defined functions into DDW, and the DDW log file displays the following message,

"An attempt was made to load an assembly from a network location which would have caused the assembly to be sandboxed in previous versions of the .NET Framework. This release of the .NET Framework does not enable CAS policy by default, so this load may be dangerous. If this load is not intended to sandbox the assembly, please enable the loadFromRemoteSources switch. See http://go.microsoft.com/fwlink/?LinkId=155569 for more information."

Then, add the following configuration in the Data Exchange Development Workbench.exe.config file available in the DDW installation folder.

 <runtime>
 <loadFromRemoteSources enabled="true"/>
 </runtime>

If you want to run the transformation in Data Exchange Runtime Service, add the above configuration in the Data Exchange Runtime Service.exe.config file available in the Runtime Service installation folder, and then restart Runtime Service.