Having difficulty obtaining a credit card.

I am a 24 years old student with a part time job. I never have below $2,000 in my bank account. I need to start building my credit. I have applied online three times at TD for their Green Visa card and denied on all three occasions. I think I am good when it comes to managing my money and I hate the idea of a loan or debt. My only reason for wanting a credit card now is to build credit and for convenience (online shopping / bills). Any help is greatly appreciated.

Thanks!