This will cause an error in code if reader1[0] is null:
SomeVariableName += Convert::ToInt32(reader1[0]);
Use this to detect if it is null:
if (!reader1->IsDBNull(0))
SomeVariableName += Convert::ToInt32(reader1[0]);
Feel free to comment if you can add help to this page or point out issues and solutions you have found. I do not provide support on this site, if you need help with a problem head over to stack overflow.