ANSEL = 0; // Configure AN pins as digital I/O
ANSELH = 0;
C1ON_bit = 0; // Disable comparators
C2ON_bit = 0;
it gives all above registers as undefined......
Mikroc uses same name as in PIC microcontroller's datasheet.
Choose the right device from project-->edit project.
These 4 registers in 16f887, And it will give error when ur device is 16f877a.
Its very difficult to find MikroC header file because all are in precompiled library.
Use the Help document instead.