Is there a problem with the computed value on Line 1 of Colorado Form 104? A negative value is being entered even though the Federal Form 1040 Line 15 is 0.

My Federal income is negative this year, but it is reported (per instructions) as $0 on my Form 1040 Line 15.  Okay, now onto State.  Line 1 on my Colorado Form 104 Line 1 says to enter the number from Federal Form 1040 Line 15.  But instead of $0 (which is the number on the form), the negative income value is being entered.  This doesn't seem right.