Line Tag Annotation Plant_area

Hi I am tyring to add PLANT_AREA field in Line tag annotation. But lts not working. I am using following:

ECExpression : this.PIPELINE_NAME & "-" & this.SIZE & "-" & this.PLANT_AREA

Failure vaule: Tag-Size-Area

This is giving following output

"0003-80-Area"   Means area somehow not getting in .