Why am I restricted on instant deposit?

We allows instant buying power on the good faith that your transfers will go through. The reversal of your incoming deposit may result in the restriction of getting instant buying power.

Why do I get access to zero buying power on my deposit?

The most likely reason would be that you have exceeded your instant deposit limit. 

For example, your instant deposit limit is $1000, if you make a $2000 deposit from your bank, only $1000 can be accessed.

Why can't I cancel my deposit

If you are in use of the buying power we granted, you can not cancel the deposit. If you want to cancel it, you can first close the related positions, and then cancel it accordingly.