LCD

I want to program the text to a 2 line 5 x 7 LCD module. But before I do
that in a language I am experimental with just the LCD module with a push
button for the clock or enable signal and some DIP switches for the data
signals. When I finished setting up the LCD and proceed to input letters to
the LCD, some letters are fine however some letters come out incorrectly. I
adjust the DIP switches for the appropriate hi's and lo's for that letter
however, when I clock the data into the LCD, a different character comes up
and when I clock it again and again, I get different letters. I notice
however that the letters that are different sometimes have similarities in
the binary number either in the high nibble or low nibble. Is my LCD busted?
It's a new one and took me ages to wire this thing up. I am using breadboard
to hold it all together. What could be the source to this problem?