using overloading in calculator

Question

hello every one ;
i am creating a calculator using overloading function in c-sharp.
the problem is , if i press two button then the answer more then one . for e.g , i press 1+2 the real answer should be 3 but the answer is getting 4. if i press three button like 1+2+3 the answer should be 6 but the answer is getting 7. so i realize that the problem is occuring in the function calling because without overloading there is no error in this application .
plz help me .
thanks to all of you.
regards
sumaira