Item Being Used before Gear in Macro

I am trying to use a macro that will use my Frag Bomb Tinker for a free bomb inside my normal grenade macro.

The macro is:
#showtooltip
/cancelaura ice block
/use Frostsavage Belt
/use iron grenade
/use thorium grenade
/use adamantite grenade
/use cobalt frag bomb
/stopcasting

The problem is that it won’t use my belt if there are one of the items in my inventory. This seems like a bug.

Reverse the order. Assuming it uses a reticle, only the last one in the list will be usable.