In order to make a Deductible Traditional IRA Contribution, you must be under the age of 70 1/2 as of 12/31/18 and have earned income from a W2 or Form 1099-MISC at least $12k, the amount of your contributions.
Also, be sure to double check your W2 to make sure the Pension Plan Box 13 is not checked on any of them.
If none of this applies to you, please comment below.