Yes,

40 KHz is well within the IR modulation range. I suggest don't change it.

One thing that I can think of is mainly the quality of the IR LED you are using.

Increasing the current is no solution. How far can you increase, even beyond the LED rating ??

I beleive the LED you are using is of some poor quality on one hand and the it is squint eyed LED , hehehehehe.

Yes, often that's a problem. Try changing angle you will feel the difference.

I will try to ge some good quality IR LEDs from Lahore and let you have them.

See the range of SONY remote is more than 25 feet just with a single LED. Threre is not much magic in that but the quality mainly, which is lacking in your LED, I think.

Just wait,

Good luck

Babar/