how to use switch to control output?

there are 4 switches where i named it as button1, button2, button3, button4
and they are originally connected to 2.5v.
once i press the button, it'll go to LOW.
When PIC detect LOW from the input, output=1.
However, the program i did was not functioning well...it execute "LATBbits.LATB2=1" even when i did not press the button( input is still high).
anyone know what mistake had i did?

this is my program:

#include "p18f24k20.h"

#define button1 LATAbits.LATA1
#define button2 LATAbits.LATA2
#define button3 LATAbits.LATA3
#define button4 LATAbits.LATA4

#define ON 1
#define OFF 0

void main (void)
{
LATA= 0x00;
TRISA=0b00011110;/* initialize RA<4:1> as input*/
LATB= 0x00;
TRISB=0b11100011;/* initialize RB<4:2> as output*/
LATC=0x00;
TRISC=0b11001011;/* initialize RC<5:4> and RA2 as output*/

while(1)
{
if(!button1)/*PIC detect LOW*/
{
LATBbits.LATB2=1;
}
else if(!button2)
{
LATBbits.LATB3=1;
}
else if(!button3)
{
LATBbits.LATB4=1;
}
else if (!button4)
{
LATCbits.LATC2=1;
}
else
{
LATBbits.LATB2=0;
LATBbits.LATB3=0;
LATBbits.LATB4=0;
LATCbits.LATC2=0;
}
}
} //main

Take a look at the ANSEL register.
On power up port A pins are configured as analog input pins. You have to clear the ANSEL register bits to make them digital I/O.

check LATAbits

yes, you use the lat bits to set the output, but use the port bits to read the input.

Thanks for ur guide, here are my program after those correction and it's working now.

#include "p18f24k20.h"

#define button1 PORTAbits.RA1
#define button2 PORTAbits.RA2
#define button3 PORTAbits.RA3
#define button4 PORTAbits.RA4

void main (void)
{
ANSELbits.ANS1=0;
ANSELbits.ANS2=0;
ANSELbits.ANS3=0;
ANSELbits.ANS4=0;
PORTA= 0x00;
TRISA=0b00011110;/* initialize RA<4:1> as input*/
LATB= 0x00;
TRISB=0x00;/* initialize RB<4:2> as output*/
LATC=0x00;
TRISC=0x00;/* initialize RC<5:4> and RA2 as output*/

while(1)
{
if(!button1)/*PIC detect LOW*/
{
LATBbits.LATB2=1;
}
else if(!button2)
{
LATBbits.LATB3=1;
}
else if(!button3)
{
LATBbits.LATB4=1;
}
else if (!button4)
{
LATCbits.LATC2=1;
}
else
{
LATBbits.LATB2=0;
LATBbits.LATB3=0;
LATBbits.LATB4=0;
LATCbits.LATC2=0;

}
}
} //main