opt: undefined symbol: _ZN4llvm9DebugFlagE

Hi list,

I try to run my pass by executing:
opt -load …/…/…/Release+Asserts/lib/MyPass.so -MyPassName

But I get this error:

Error opening ‘…/…/…/Release+Asserts/lib/MyPass.so’: …/…/…/Release+Asserts/lib/MyPass.so: undefined symbol: _ZN4llvm9DebugFlagE
-load request ignored.
opt: Unknown command line argument ‘-MyPassName’. Try: ‘opt -help’

I’ve googled this error but everything I find is about ‘enabling assertions’ that I’ve already done.
This error seems quite weird to me as I was running successfully my pass until I changed the src folder.
After adapting accordingly the paths on the makefile, I get the above error.

I’d really appreciate any help on this.
Thanks in advance,

Is your "opt" built with NDEBUG?