Trade-O-Mat not working?

[htcmicah]

I've been trying to get this thing working and have had no luck.  First I tried it with the personal safe.  It won't take items from the safe.  I try it with a chest, though, and it works.  Secondly, it resets every time a trade is made.  If I give one diamond for two uranium, for example, every time someone puts in their two uranium they get their diamond.  But, the two uranium I have in the top left slot disappear.  

 

Why won't the personal safe work?  And do I have to reset the Trade-O-Mat after every single trade?