Lav mic setup confusion
 

Very excited having purchased my first wirelass lav mic system.

Now however, very confused with how to set this up with my XL-H1a. What i'm trying to do is record vocal into the lav mic but also have the onboard mic pickup other ambient noises. When I connect the lav mic into CH1 XLR and set CH1 to 'XLR MIC' and monitor the sound through headphones, the left channel is only picking up the lav mic and the right channel is only picking up the sound from the onboard mic.

Is there a setting i'm missing here to balance the sound out ?

Nope, that's exactly how it works. Channel 1 feeds the left and Channel 2 feeds the right. It's actually better to do it that way because in post you can then adjust the lav and on board mic separately. If your wireless lav takes an interference hit, you have backup audio coming from the on-camera mic.

Ok thanks Edward, just thought there might have been a setting somewhere to mix the sound, but maybe not.

As Edward mentioned, it would be very rare that you would want to mix the audio being recorded. Once it's mixed, it can't be separated or treated differently in post-production.

Some additional points with the XL-H1a:
You may want to switch the on-board mic from stereo to mono so that its track is evenly pickup up from in front of the camera. This won't change the condition you originally asked about, it will simply give more even pickup from the onboard mic since you're just using it as one channel.

If you are uncomfortable monitoring on headphones what you are recording with the lav only in one ear and the ambient only in the other, you will need to connect the audio RCA output connectors to a mixer that can allow the sound from both sources to be in both ears.
This will allow you to hear what the mix will sound like in post without actually mixing them in the recording. It's better to use a mixer rather than just a "Y" cable because some headphone outputs can be damaged if they are operated long-term with the Left and Right shorted together.

Some camera's have a monitor switch that will allow mixing the Left and Right channels in the headphones, but the XL-H1a only allows for monitor mixing 4 channels together if you are recording in a 4 channel mode, but not if you are working just with 2 channel audio.

In post-production, depending on your editing software, it is easy to adjust and mix the two channels as needed for final output.