Ampscript IF NOT EMPTY

I am trying to check if a field is empty. If not empty, check if 1 of the 3 numbers is in that field, and if so, display a string of text. It's not working; any feedback would be great.

Cheers,W

        %%[            VAR @Headline, @TriggerCode, @PlanCode                SET @TriggerCode = AttributeValue("ZZ_SD_MAT1")                IIF NOT EMPTY(@TriggerCode) THEN                    SET @PlanCode = AttributeValue("TriggerCode")                        IF @PlanCode == "3001078" THEN                            SET @Headline = "Thank you for choosing the Smart Energy Savings Bundle"                        ELSEIF @PlanCode =="3001088" THEN                            SET @Headline = "Thank you for choosing the Smart Energy Savings Bundle"                        ELSEIF @PlanCode == "3001089" THEN                            SET @Headline = "Thank you for choosing the Smart Energy Savings Bundle with Vivint HomeProtect Pro"                        ELSE                         ENDIF                ELSE                    SET @Headline = "Thank you for choosing Reliant"                ENDIF        ]%%<tr><td align="left" valign="top" style="font-family: 'EffraLight', sans-serif; font-size:20px; line-height: 46px; font-weight:bold; color:#392E8E; text-transform: none;" class="mobile_headline_4">            %%=v(@TriggerCode)=%%<br>            %%=v(@Headline)=%%</td></tr>