Custom dtb won't work

I have an existing dts file called: am335x-boneblack-pruswuart.dts. I want to put the bb-uart1-00a0, bb-uart2-00a0, bb-uart4-00a0, bb-uart5-00a0 dtbo's in the am335x-boneblack-pruswuart.dts. 

#include <dt-bindings/pinctrl/am33xx.h>

/*
 * Free up the pins used by the cape from the pinmux helpers.
 */
&ocp {
	P9_24_pinmux { status = "disabled"; };	/* uart1_txd */
	P9_26_pinmux { status = "disabled"; };	/* uart1_rxd */
};

&am33xx_pinmux {
	bb_uart1_pins: pinmux_bb_uart1_pins {
		pinctrl-single,pins = <
			AM33XX_PADCONF(AM335X_PIN_UART1_TXD, PIN_OUTPUT, MUX_MODE0)	/* P9_24 uart1_txd.uart1_txd */
			AM33XX_PADCONF(AM335X_PIN_UART1_RXD, PIN_INPUT, MUX_MODE0)	/* P9_26 uart1_rxd.uart1_rxd */
			//AM33XX_PADCONF(AM335X_PIN_UART1_RTSN, PIN_OUTPUT, MUX_MODE0)	/* P9_19 uart1_rtsn.uart1_rtsn */
			//AM33XX_PADCONF(AM335X_PIN_UART1_CTSN, PIN_INPUT, MUX_MODE0)	/* P9_20 uart1_ctsn.uart1_ctsn */
		>;
	};
};

&uart1 {
	/* sudo agetty 115200 ttyS1 */
	status = "okay";
	pinctrl-names = "default";
	pinctrl-0 = <&bb_uart1_pins>;
};

I copied this in the am335x-boneblack-pruswuart.dts file. Converted it to a dtb file. And changed the uEnv.txt to : dtb=am335x-boneblack-pruswuart.dtb.

However when i reboot then there is no ttyS1 interface if i do 

dmesg | grep tty

And if i do: 

echo "test" > /dev/ttyS1