I live in RI but earn all my money from a MA source. Why is it that on my RI return, it says your tentative credit for taxes paid to MA is zero

When you file your RI state return,

1. On the screen that says Other Rhode Island Tax Situations, select this box Taxes Paid to Other States
2. Answer Yes to the question Did you pay state income taxes to Rhode Island and to another state on the same income?

But before your get here, make sure you complete MA non-resident return first.