Cannot load 'mcMath.dll' [126]

[fadisal]

I have write this simple dll in c#

namespace mcMath
 {
     public class Class1
     {
        public static double addUp(double num1, double num2)
         {
             return (num1 + num2);
         }

    } 

} 

when I try to import this dll file to metatrader4 I get an error Cannot load 'mcMath.dll' [126].

    10:55:17.373    Expert fadi EURUSD,H4: loaded successfully
0   10:55:17.689    Expert fadi EURUSD#,H1: loaded successfully
3   10:55:19.224    Cannot load 'mcMath.dll' [126]
0   10:55:19.225    fadi EURUSD,H4: initialized
3   10:55:24.027    Cannot load 'mcMath.dll' [126]
0   10:55:24.028    fadi EURUSD#,H1: initialized
1   10:55:27.463    Cannot call 'mcMath.dll::addUp', 'mcMath.dll' is not loded    
1   10:55:27.494    fadi EURUSD#,H1: unresolved import function call
0   10:55:27.522    fadi EURUSD#,H1: uninit reason 4
0   10:55:27.538    Expert fadi EURUSD#,H1: removed
I have allowed dll imports Anyone had the same problem and solve it?
mql4 code:
#import "mcMath.dll"
   double addUp(double number1,double number2);
   #import
   double number1, number2;
   int OnInit()
   {
  //---
      number1=10.5;
      number2=20.3;
      double number3= addUp(number1,number2);
      Print("the result is: " + number3);
   //---
   return(INIT_SUCCEEDED);
    }