Dear Bruno, The problem is simple: the variable "logarea" is not equal to "yhat1".
logarea yhat1
1 13.73169 17.32861
2 13.88510 16.59191
3 14.90278 9.24835
4 10.38514 43.42590
5 5.48064 80.59877
6 10.92590 37.84531
...
Um abraço,
Henrique
