Qwt examples are working but,Not able to run selfdesigned qwt applications!

[Krish]

Hello! Friends,
I am working in WinXp with Qt4.3.4. Also i have installed qwt library and can use qwt plugin in Qt. All the qwt examples are compiled and working properly.

But today i tried to design a simple GUI widget form containing 2 pushbuttons & QwtPlot widget, but getting following error's.

In file included from main.cpp:3:
sampleplot.h:5:22: qwt_plot.h: No such file or directory
sampleplot.h:7:28: qwt_plot_curve.h: No such file or directory
sampleplot.h:8:27: qwt_scale_map.h: No such file or directory
In file included from sampleplot.h:10,
from main.cpp:3:
ui_sampleplot.h:30: error: ISO C++ forbids declaration of `QwtPlot' with no type

ui_sampleplot.h:30: error: expected `;' before '*' token
ui_sampleplot.h: In member function `void Ui_sampleForm::setupUi(QWidget*)':
ui_sampleplot.h:54: error: `sampleqwtPlot' was not declared in this scope
ui_sampleplot.h:54: error: `QwtPlot' has not been declared
In file included from main.cpp:3:
sampleplot.h: At global scope:
sampleplot.h:16: error: expected class-name before ',' token
sampleplot.h:37: error: ISO C++ forbids declaration of `QwtPlotCurve' with no ty
pe
sampleplot.h:37: error: expected `;' before '*' token
main.cpp: In function `int qMain(int, char**)':
main.cpp:8: error: 'class samplePlot' has no member named 'show'
main.cpp:11:2: warning: no newline at end of file
mingw32-make[1]: *** [release/main.o] Error 1
mingw32-make[1]: Leaving directory `C:/Shishir/Self Examples/Sample_Plot'
mingw32-make: *** [release] Error 2

From this it seems that it is not able to find the qwt files, but all qwt examples are working that means it can find them!!!!

Can anyone please help me out in this.-->I will be obliged.

Thanks in advance.