Hi I'm studying with aspen plus program but I'm having problem which i can't solve ㅠ

I try to design biomass process so I add conventional component first and then try to add solid component. After adding Cellulose solid component , and add solid enthalpy of formation as user-defined component. And then I add acetic acid solid component. At first there was no problem but when I add solid enthalpy of formation of acetic acid as user-defined property, it showed error on control panel like this...

If you have any idea please help me.