Stratix II ES180 board, help me with DAC output

I don't know the board itself but there is a mismatch between your code and your text. In you code, you are defining a parallel output for the DAC, using 14 signals, but in your text you are talking about a single pin, suggesting a serial output. If the DAC's input is a serial signal (which I suspect it is) then you need to do a parallel-to-serial conversion in your FPGA code.