can access to heavy weapon upgrade

[カミーユ・ビダン]

I have reach to mahattam level of story mode. But I cannot access to it due to some technical issue. Do anybody know how to solve it?

[Back Yard Gamer]

Do you mean you cannot pickup the weapon upgrades?

There's four to collect in the manhattan area. One upstairs in the first area, one in the Subway, one upstairs near where the Big robot is. And final one in the penthouse.

[カミーユ・ビダン]

no, I can pick up weapon upgrade, just not able to use to upgarde the heavy one that was available

[Back Yard Gamer]

If you are using a keyboard did you try pressing J to open the menu then select weapons and pick the one you want to upgrade.

The Big lasers and Diesel guns the Big guys use are not upgradable. You just get extra ammo for kills...