You could have not gotten it because your Modified Adjusted Gross Income (MAGI) is above the limit.
This, from IRS Tax Topic No. 607:
For tax year 2018, the MAGI phaseout begins at $207,140 and ends at $247,140. Thus, if your MAGI amount is below $207,140 for 2018, your credit or exclusion won't be affected by the MAGI phaseout, whereas if your MAGI amount for 2018 is $247,140 or more, your credit or exclusion will be zero.