[Rd] dyn.load error -- undefined symbol: ...

[nwew]

Dear R-developers,

I am working on an C interface to some c functions.
I compiled the c file using R CMD SHLIB without any compilation errors. All 
libs used are added to the LD_LIBRARY_PATH.

However dyn.load("interface.so")
produces  undefined symbol: N_VNew_Serial;

which is defined in one of the libs I link against.
Where, and how to start searching for the error?

Eryk