Problem: lcd.print("mm/h");

I have a problem with my 16x2 LCD screen. The first line is used for a title and the second line is used for showing a speed.

In the void setup I'm making the template by printing the title "camera winch" on the first line and printing mm/h on the end of the second line. I found out that using the slash in the unit the first row of the LCD is fully lid and the second stays dark. When I loose the slash everything works fine.

Why is this? and is there a way to print a slash

void setup() {
  lcd.begin(16, 2);
  lcd.clear();
  lcd.setCursor(1,0);
  lcd.print("Camera Winch!");
  lcd.setCursor(12,1);
  lcd.print("mm/h");                  //millimeter per hour = mm/h

There are different models of 16x2 LCD... which one are you using? Post link to datasheet.

LCD Display HD44780

http://arduino.cc/en/Tutorial/LiquidCrystalDisplay

I don't own that LCD, but try:

lcd.write( 0b00101111 );

Source: https://www.sparkfun.com/datasheets/LCD/HD44780.pdf

FYI: I tested your code on a 16x2 LCD that I bought from here and it works just fine.

Pete