How do I Fix this "Error at line number : 0 Mismatch data type for function 'GetType' at argument index 1 expected data type BIGINT found data type STRING"

How do I Fix this "Error at line number : 0 Mismatch data type for function 'GetType' at argument index 1 expected data type BIGINT found data type STRING"

Good Day, 

I am trying to return a result from Credit field and I keep getting this message:

Error at line number : 0 
Mismatch data type for function 'GetType' at argument index 1 expected data type BIGINT found data type STRING

I Don't understand because everything seems correct.

Function:
string externalapps.GetType(int name)
{
    //GetType is the name of the function
    if (Add_Rep[ID == input.name].count()  >  0)
    {
        //"Add_Rep" is the form link name
        return Add_Rep[ID == input.name].Allow_Credit;
        //"Credit" is the field deluge name
    }
    return "";
}

Field Action

input.Credit = thisapp.externalapps.GetType(input.Rep_Name);