Linker Errors - while generating a build for THUMB

Was succesfully able to build a exe, with some code on wins using the following commands
bldmake bldfiles
abld build wins urel

However, when used the same code and same mmp files for generating the exe for THUMB, i get a number of linker errors.
For generating the exe for THUMB used the following commands,
bldmake bldfiles
abld build thumb urel

Many of the errors are undefined references to the symbian system functions like,

undefined reference to `CBase::newL(unsigned int)'
undefined reference to `CBase::CBase(void)'
undefined reference to `CleanupStack::Pop(void)'
undefined reference to `CBase::~CBase(void)'
undefined reference to `RSemaphore::CreateLocal(int, TOwnerType)'
undefined reference to `User::LeaveIfError(int)'
undefined reference to `CActiveScheduler::Add(CActive *)'
etc etc

We have included system includes/libraries in the mmp file, as
SYSTEMINCLUDE \Epoc32\include \Epoc32\include\libc \Epoc32\include\libc\sys

LIBRARY euser.lib insock.lib esock.lib efsrv.lib estlib.lib
LIBRARY certstore.lib ctframework.lib crypto.lib wtlscert.lib
LIBRARY cryptalg.lib bigint.lib hash.lib random.lib privkey.lib

Am I missing out on something here ? Do we need to do something differently for thumb ?

Please can someone throw some light, on why am i getting these linker errors, while generating the exe for thumb.

Thanks in advance for all the help.