Good day all you great visio users

Wondering if you could help me out here. I have some Page shape data setup, one of the fields is a list of persons names to be chosen on a drop down and then in another i have a formula to show the persons phone number automatically. thing is, when i change the persons name i can see in the shape sheet that the value changes for the phone number but it does not update on the drawing shape data window. If i select the formula and just hit enter without changing anything then it does update.
the formula i have in the Value column for the phone number is " =IF(STRSAME(Prop.Contact_Person,"Eddie",1),"555-5555",IF(STRSAME(Prop.Contact_Person,"Frank",1),"444-444","0"))
I have the Type set to 0 with "No Formula" in the Prompt
Hopefully an easy fix

Thanks all!