Case Merge – "Insufficient Access right to the user" error

I recently installed case manager app by Algoworks into my main org. On a custom profile that was created for my service desk when trying to merge a set of cases, one of my users is getting an “Insufficient Access right to the user” Error

• This discussion was modified 8 years, 7 months ago by  Forcetalks.
• This discussion was modified 8 years, 7 months ago by  Forcetalks.
• This discussion was modified 8 years, 7 months ago by  Forcetalks.
• This discussion was modified 8 years, 7 months ago by  Forcetalks.
• This discussion was modified 8 years, 7 months ago by  Forcetalks.