Crossbow Shot not Changing Weapon Set

Ex: I have my Crossbow Shot in weapong I for Explosive Shot and the grenades in set II.
When I use a Explosive Shot e right and immediatly a Grenade, the Explosive Shot load goes to 0, doesnt reload, and when I click in the Crossbow Shot, it just dont go back to Weapon Set I, so i can use the Explosive SHot.