Found no calls to: 'R_registerRoutines', 'R_useDynamicSymbols' unresolved

I've been strangling with an unresolved 'R_registerRoutines', 'R_useDynamicSymbols' note from R CMD check. I have read the relevant Section in the 'Writing R Extensions' and also checked various other posts online but the problem persists.

Summary of what I have done:

1. I created the init.c file put in the src/ directory with the following content given in [1] below. This was done using tools::package_native_routine_registration_skeleton(".", "src/init.c", character_only = FALSE) (because with the default character_only = TRUE was not working).
2. I checked if the same names appear in RcppExports.cpp in src/ and RcppExports.R in R/ given in [2] below.
3. I have added useDynLib(JMbayes, .registration = TRUE) in the NAMESPACE.

Hence, any pointers would be welcome!

[1] init.c

[2] RcppExports.cpp