Inconsistent accessibility parameter:RestAPi in C#

Question

Hi Team

 

I need some help, i have a public class object(CoinJar) but the problem now it does not seem to find void AddCoin(coinType....) its throwing an error "inconsistent accessibility parameter. How do i resolve this issue? 

//CoinJarController
 [HttpPost]
         void AddCoin([FromBody]eCoinType coinType, [FromBody]int count = 1)
        {

            this.coinJar.AddCoin(coinType, count); //Inconsistent accessibility parameter.
        }

//CoinJar.cs
 public class CoinJar
        {
        private readonly Coins[] coins = Enum.GetValues(typeof(eCoinType)).Cast().Select(t => new Coins(t)).ToArray();

        // default constructor.
        public CoinJar()
        {

        }

        // Add method.

         void AddCoin(eCoinType coinType, int count = 1)
        {
            coins.First(t => t.CoinType == coinType).Amount += count;
        }
}