Many warnings when compiling template class

I am working on WindowsXP with ROOT 5.16.00
For the first time, I have tried to write a class containing a template. This class, with the makefile.mak is included in this mail as file NArray.tar.gz. It can be compiled and linked in the “command prompt window” with
nmake -f makefile.mak
Compilation and link succeed, and the .exe seems to work. The problem is that I have an awful number of warnings of the type:

TNArray.cxx(130) : warning C4661: ‘TClass *TNArray::fgIsA’ : no suitable definition provided for explicit template instantiation request
with
[
T=Long_t
]
d:\sv\projetspp\forroot\narray\TNArray.h(71) : see declaration of ‘TNArray::fgIsA’
with
[
T=Long_t
]

Is there something wrong in my makefile.mak? Does it mean that I will have problems when trying to write this class into a ROOT file or storing it into a ROOT collection? Thanks a lot for your help.
NArray.tar.gz (6.14 KB)

This is an expected harmless warning message , disable it by adding the flag: “-wd4661” to your compile line.

Cheers,
Philippe