https://www.everquest.com/news/imported-eq-enus-51037 Are you typing "/claimVeteranReward" like your title or "/veteranreward"
Just read the message and type in what it tells you to type in; it should work. Note that if this is your first year getting a veteran reward, you'll only be able to claim it on one character. So if you have multiple characters, be sure you claim it on the right one. Each additional year will give you a new reward and allow you to claim the rewards on an additional character.
keep it simple.. all I have ever typed in is /claim and it brings up the window to claim my veteran rewards..
/claim and /veteranreward are two totally different things. /claim lets you get items which you've gotten from expansion purchases or promotions or other such things into your inventory, and /veteranreward is a set of abilities (passive and active) which you unlock for your character, such as the daily exp boost for half an hour, or the ability to summon an NPC vendor or banker familiar to your location, earned by having an account for X number of years, up to I believe 14.
There's a good write-up on Veteran Rewards on Fanra's web site, at: http://everquest.fanra.info/wiki/Veteran_Rewards Going by the way it's working on my account, the number of years used for Veteran Reward eligibility is the same as the number of 'entitled' years listed when you use the '/played' command.
Just a warning if you don't know. Once you claim the Vet Reward on a character, you have burned that request. If you delete the character, you do NOT get the reward back to be able to claim it on a different character. I found that out years ago the hard way. I granted the reward on a test character, decided to go a different route, deleted him, trued to grant the reward on the new character, and found out I didn't have any rewards left. BUMMER! Just be sure that who you grant the reward to is the character you want to keep.