Building using 6.2 with 6.3 on same dev platform

I have installed version of 6.2.1 and 6.3.
I can make our 6.3 projects ok, but I cannot make our 6.2.1 projects.
I use the ‘QNX Momentics Configuration’ program to setup for the 6.2
environment, but the builds always fail with the following error:

make PROJECT_ROOT_ProgCommon=H:\TestProj\Common CPULIST=x86
Makefile:8: No such file or directory
make: *** No rule to make target'. make: Failed to remake makefile’.
make: *** No targets. Stop.

This used to work before I installed 6.3. Any help is appreciated and