FileIOPermission failed for assembly with FullTrust Permission Set

After setting fulltrust for an .net assembly to enable it to run from a network share I ran into a figured got into an exception saying: Request for the permission of type ‚System.Security.Permissions.FileIOPermission, mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089‘ failed. Source: mscorlib StackTrace: at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.IO.DirectoryInfo..ctor(String path) After trying a while I figured out, that this occures if the code group points to a single assembly. As soon as I pointed it to the whole directory it worked. This might be because other assemblies are used by the main application. The call I used to set the code group is caspol.exe -machine -addgroup LocalIntranet_Zone -url „z:\pathtofile\*“ FullTrust -name „mynewcodegroup“