I think you are a bit confused.
What does matter is that the IR LED transmits at the same wavelength as that which your receiver receives at.
That is, if your receiver states that its sensor picks up 940nm waves, then make sure that your LED is a 940nm LED.
Think of it as a language:
There are two people, Person A and Person B. They are trying to send a message to each other. So long as Person A speaks a language Person B understands, then all is good - ie. the goal was to send a message, successful.
Say, Person A speaks in German. Therefore, Person B must understand German. Person A speaks in English, Person B must understand English. LED transmitts at 940nm, IR receiver must be able to receieve at 940nm.
Alternatively, if Person A speaks German but Person B doesn't understand German, then we have aproblem. If the LED transmits as 940nm but the IR receiver is sensitive to only 890nm, then we have aproblem.
Hope that clears it up.
<b><i>ylp88 </b> </i>