It may be a fault in the keyboard driver or in the keyboard itself. However if the character you need is not available on the keyboard directly it is possible to get any character by using the ASCII char code entry method. First off search the internet for a ASCII character number associating table (for a chart I like best, check here http://michaelgoerz.net/blog/2008/09/ascii-table/ascii.gif)
now on this chart you have to use common fonts (IE: Ariel, times new roman, ect.) because some of the TTF fonts do not have all the characters in them available.
Now to practice using the characters, load Notepad and find the character you want to display from the chart (note: the number like 000d and 00h actually means 000 decimal and 00 hexadecimal, only use the number with the "d" after it with this method), on Notepad, after you pick out the character you want to display, press and hold the ALT key, and on your keypad (on most keyboards it is on the right side and resembles a calculator type keypad) while holding the ALT key down enter the number of the character you want to display (do not include the "d", only the number) then release the ALT key and that character should display for you in Notepad. Almost all standard fonts has the regular characters and some has the extended characters, you will have to check to see if the font uses them by trial and error. this method is a long lost forgotten means of putting characters into your documents which does not have keys on a standard keyboard (most standard keyboards only have 101 keys so this is the only way of using all the 255 character available in common fonts).
This is a built in function of all computers that uses Microsoft OS's and even DOS, HDOS, EDOS, (well all the DOS's), and you can use them anywhere you can type anything from your keyboard, (emails, letters, databases, spread sheets, etc.) if you can type from the keyboard to any program you can use these characters in this manner.
I hope this help you out!