unable to use fread() function

Hi,

I am working on MCB2300 (with LPC2378 processor). I have written a small function that will read the values into a matrix. But when the control comes to fread it completely hangs up, nothing can be done. Below is the my function which is giving problem

 void loadImage(FILE* arq, unsigned char** Matrix){
        int i,j;
        unsigned char tmp;
        long pos = 51;

        fseek(arq,0,0);

        for (i=0; i<300; i++){
                for (j=0; j<400; j++){
                        pos+= 3;
                        fseek(arq,pos,0);
                        fread(&tmp,3,1,arq);
                        Matrix[i][j] = tmp;
                }
        }
}

Its working fine in GNU C. But when I have tried to use the same code in Keil uVision4, its is not working. Please let me know how to sort this problem