Position grades aren’t synchronized into assignment after HDL load what could be the reason ?

Hello,

we manage the employment details , at the position level .

When performing a HDL load of The of the position details ,, All the data was uploaded in the position successfully. 

Then we ran the synchronize process from position to assignment. 

All the employees have “ synchronize form position field” set to Y  

The data of the position name and job was synchronize successfully from the position automatically after running the process ,but the grades weren’t synchronized and not updated in the assignment .  

I ran in HDL - position part and also position grade - including grade code and valid grad