[SOLVED] Developing a new package that depends on another OpenWrt package

The problem is SOLVED.

Through this thread: [probably solved] How to build on debian 9? Missing libpam, libgnutls,

And by adding this option:
-lmosquitto
at the end of the second line of Package build instructions (Build/Compile) section in Makefile, like that:

$(TARGET_CC) $(TARGET_LDFLAGS) -o $(PKG_BUILD_DIR)/$1 $(PKG_BUILD_DIR)/mynewpackage.o -lmosquitto

Thanks,