Why i cant lvl up barret cobalt vip from 200 to 250 exp?

BrainDrain

I upgraded my ak red eye from 200 to 250exp bonus but cannot do same for barret cobalt vip and 9a vip? Any help?

[MOD]ShadowRo

Not all VIP items have " upgrade option" to upgrade EXP/GP bonus perks.

Example of VIP items without upgrade option : 
9a-91 Wild Eagle
M200 CheyTac-Dominator
Barrett M82A1-Jewerly

D.E. Obsidian Beast
D.E. El Dorado
Ragging Bull-Cyborg

and Barret Cobalt is one of them.