[pdftex] no BoundingBox

[riccardo nisi]

I am Riccardo Nisi and I write a very bad English.
My computer is MacMini, OSX  10.6.
I am using TexShop + Latex and the MacTex 2007 package.

(1) I am using TexShop and Latex with the PSTricks package for to  
produce mathematical
graphics, and the first line of my source file (we say qqq.tex) is  
%TEX TS-program = latex.
TexShop typesets my qqq.tex and the output is qqq.pdf.

(2) I crop the file qqq.pdf with the Preview application and  save the  
new qqq.pdf.

(3) I am in need of to insert the separate graphics into an other  
source file, wich uses
the PSTricks package (the first line is %TEX TS-program =latex), with  
\incudegraphics{qqq}.

(4) When I tipeset the (3)sourcefile, TexShop says that it does not  
find the  qqq file.
If the  \includegraphics argument is qqq.pdf, TexShop says that the  
graphic file has no
BoundingBox.

I ask you as or if it is possible to solve these problems with  
TexShop, also using the Terminal.
I will be grateful to you for your kind reply.

Riccardo Nisi