The failure of unmanaged code(Delphi) consumes Com from .Net

We have  to access  a Com dll that is developed by C#,    when its codebase register(regasm) as local path, works fine. but when its codebase is mapped driver, it throws the error "interface not supported" by Delphi7. From FUSLOGVW.exe, find the Com DLL has bound successfully.  also I tested to use Caspol.exe to grant full trust to mapped driver, like:

Caspol.exe -m -ag 1.2 -url file://S:\ComClass.DLL FullTrust.

I'm wondering if the managed com dll can not be registered as mapped driver????

*** Assembly Binder Log Entry  (2013-11-8 @ 15:28:14) ***

The operation was successful.
Bind result: hr = 0x0. The operation completed successfully.

Assembly manager loaded from:  C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\mscorwks.dll
Running under executable  D:\project\TestCom.exe
--- A detailed error log follows. 

=== Pre-bind state information ===
LOG: User = JASON-DELPHI7WI\Dev
LOG: Where-ref bind. Location = S:/ComClass.DLL
LOG: Appbase = file:///D:/project/
LOG: Initial PrivatePath = NULL
LOG: Dynamic Base = NULL
LOG: Cache Base = NULL
LOG: AppName = TestCom.exe
Calling assembly : (Unknown).
===
LOG: This bind starts in LoadFrom load context.
WRN: Native image will not be probed in LoadFrom context. Native image will only be probed in default load context, like with Assembly.Load().
LOG: No application configuration file found.
LOG: Using machine configuration file from C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\config\machine.config.
LOG: Attempting download of new URL file:///S:/ComClass.DLL.
LOG: Assembly download was successful. Attempting setup of file: S:\ComClass.dll
LOG: Entering run-from-source setup phase.
LOG: Assembly Name is: ComClass, Version=1.0.0.0, Culture=neutral, PublicKeyToken=ec829f3f15982550
LOG: Re-apply policy for where-ref bind.
LOG: Post-policy reference: ComClass, Version=1.0.0.0, Culture=neutral, PublicKeyToken=ec829f3f15982550
LOG: GAC Lookup was unsuccessful.
LOG: Where-ref bind Codebase does not match what is found in default context. Keep the result in LoadFrom context.
LOG: Binding succeeds. Returns assembly from S:\ComClass.dll.
LOG: Assembly is loaded in LoadFrom load context.