Control Samsung UC6300 LED backlight LCD screen with RS232

We recently moved from using projectors to LCD screens, and the screen of choice was the UC6300, which has a 3.5mm "REMOTE" control input.

Upon using the "easter egg" menu, which I can go in and change the remote control from UART, logic and diagnostic, I left it on the default UART, which I know is not normal serial 232C, however I didnt think logic was the correct item.

After this, I wired a 9pin to 3.5mm cable using the attached diagram.

Attached is some code that doesnt seem to do ANYTHING..

dvTV		= 5001:6:0	// Samsung LCD 55" -- 9600,8,N,1

VOLATILE INTEGER nTvChannels[] = 
{
    526,	// 0
    527, 	// 1
    528,	// 2
    529,	// 3
    530,	// 4
    531,	// 5
    532,	// 6
    533,	// 7
    534,	// 8
    535	// 9
}

// TV's
DATA_EVENT[dvTV]
{
    ONLINE:
    {
	WAIT 5
	{
	    SEND_COMMAND dvTV, "'SET BAND 9600,8,N,1 485 DISABLE'"
	}
    }
}

// LED TV's
BUTTON_EVENT[TPS,520]	// TV 1,2,3 Power Toggle
{
    PUSH:
    {
	WAIT 9
	{
	    SEND_STRING dvTV, "'P'" // 
	}
    }
}
BUTTON_EVENT[TPS,521]	// TV 1,2,3 Source Change Toggle
{
    PUSH:
    {
	WAIT 2
	{
	    SEND_STRING dvTV, "0,'N',1" // 
	}
    }
}
BUTTON_EVENT[TPS,522]	// TV 1,2,3 Channel up
{
    PUSH:
    {
	WAIT 2
	{
	    SEND_STRING dvTV, "'u'" // 
	}
    }
}
BUTTON_EVENT[TPS,523]	// TV 1,2,3 Channel down
{
    PUSH:
    {
	WAIT 2
	{	
	    SEND_STRING dvTV, "'d'" // 
	}
    }
}
BUTTON_EVENT[TPS,524]	// TV 1,2,3 Volume up
{
    PUSH:
    {
	WAIT 1
	{
	    SEND_STRING dvTV, "'r'" // 
	}
    }
}
BUTTON_EVENT[TPS,525]	// TV 1,2,3 Volume down
{
    PUSH:
    {
	WAIT 1
	{
	    SEND_STRING dvTV, "'l'" // 
	}
    }
}
BUTTON_EVENT[TPS,nTvChannels]	// TV 1,2,3 Number keys
{
    PUSH:
    {
	SWITCH( GET_LAST( nTvChannels ))
	{
	    CASE 1:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'0'" // 
		}
	    }
	    CASE 2:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'1'" // 
		}
	    }
	    CASE 3:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'2'" // 
		}
	    }
	    CASE 4:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'3'" // 
		}
	    }
	    CASE 5:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'4'" // 
		}
	    }
	    CASE 6:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'5'" // 
		}
	    }
	    CASE 7:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'6'" // 
		}
	    }
	    CASE 8:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'7'" // 
		}
	    }
	    CASE 9:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'8'" // 
		}
	    }
	    CASE 10:
	    {
		WAIT 1
		{
		    SEND_STRING dvTV, "'9'" // 
		}
	    }
	}
    }
}

When I press a button, the TX Led lights, however no RX light.. but the cable was tested with a cable testing and it is all correct ~ the cable is about 45 feet long, is this too long for the AMX ?

Any help on this is much appreciated !

-Paul