Compilation Error in Qt - c++

Question

I am trying to break my large project into sub directories and run it as a single executable. But when I am executing the code it is giving me the following error:
qtmain_win.cpp:-1: error: undefined reference to `qMain(int, char**)'
collect2: ld returned 1 exit status
Can anyone please explain what is the reason behind these errors...
Thanks in advance!!!!
I have made a .pro file in which all the path to the subdirectories are included. Then each directory has its own .pro and .pri file with a directory which is common in all the directories. This directory is made as a lib. Then there is a main with main.pro and main.cpp. I am pasting all the three files here: Project's pro file:
# build all components recursive
TEMPLATE = subdirs
######## normal build process ########
#
# Make sure your Main.pro is in the last line to ensure correct linking!
#
SUBDIRS =D:/MultiFuncTester/Modes/Start/Build/Start.pro \
D:/MultiFuncTester/Modes/MainMenu/Build/MainMenu.pro \
D:/MultiFuncTester/Modes/Solar/Build/Solar.pro \
D:/MultiFuncTester/Modes/Main/Build/Main.pro\
CONFIG += ordered
Main.pro:
# ################ include pri file #################
!include("Main.pri"):error("Main.pri not found")
# ################ override some pri settings #################
TEMPLATE = app
TARGET = MultiFuncTester
CONFIG =-static
QT +=core\
gui\
# ################ own sources #################
INCLUDEPATH +=D:/MultiFuncTester/
SOURCES +=../Sources/Main.cpp
Project's pri file which is common in all directories made as a lib
######################
# common stuff for all components
######################
TEMPLATE = lib
CONFIG += static \
warn_on \
qt \
QT += gui \
core \
INCLUDEPATH +=D:/MultiFuncTester/Modes \
DEPENDPATH +=D:/MultiFuncTester/Modes \
CONFIG += debug_and_release
CONFIG += build_all
CONFIG(debug, debug|release) {
CONFIG_SUFFIX = dbg
} else {
CONFIG_SUFFIX = rel
DEFINES += QT_NO_DEBUG \
QT_NO_DEBUG_OUTPUT \
NDEBUG
CONFIG(gcov) {
QMAKE_CXXFLAGS_RELEASE += -fprofile-arcs -ftest-coverage
QMAKE_LFLAGS_RELEASE += -fprofile-arcs
QMAKE_CXXFLAGS_RELEASE -= -O2
QMAKE_CXXFLAGS_RELEASE += -O0
}
}
CONFIG(crosstgt) {
#To be able to build Target run qmake as follows:
qmake CONFIG+=crosstgt
CONFIG_SUFFIX = $${CONFIG_SUFFIX}_tgt
DEFINES += TARGET_BUILD
}
OBJECTS_DIR = obj_$${CONFIG_SUFFIX}
MOC_DIR = moc_$${CONFIG_SUFFIX}
DESTDIR = lib_$${CONFIG_SUFFIX}