Is it the correct wavelength? 950 nm is popular but so is also eight-hundred something and so on..... less correct -> less sensitive receiver

Is it the correct frequency? 40? 48? 56? kHz there are plenty to choose from.... pick the wrong one and you loose performance

Do you provide enough current thru the LED? Even if the LED is specified 50 mA MAX that usually means that it can handle 50 mA constantly. Since you have a 50 % dutycycle and then send bursts out it can take much more. There is a chart in the datasheet that shows max current for different dutycycles. Now you have 30-40? More is better...... many receiver datasheets mention distance when the LED currenct is 100 mA.

I am happily running my IR led's at 700 mA and that is more than enough to change channel for the whole apartment area.

Of all these questions the easiest to solve is frequency (if you have a scope). The others are more or less up to trial and error...

Break open the TV and see if the receiver chip has any markings, then you might get both FQ and wavelength.

/me