Answered
I recently needed to open my work again and when i open the file it shows a error message:
Error in expression :label =p,exp= p(x)=if [2.56=<x<=3.98,f]
this message for four funtions and also:
processing of comand : Rotate (p,a,xAxis)
for more four functions.
it show the error and load the work blank.
Files:
TrabAM1.ggb
The same question 
Here's a version you can load at least - I've removed the bad syntax. This syntax is valid only for functions, not for lines as you've tried
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