'the multi-part identifier could not be found'

Hi guys,

I’m getting this error when I try to select and add values from my smart window to the grid which is customized by me. 

APProformaItemList is the DAC for my grid and poNbr is the foreign reference for the DAC POOrder which is used to load data into the smart panel.

following code snippet is the reference.

SelectFrom<POOrder>.
            Where<APProformaItemList.ponbr.IsEqual<POOrder.orderNbr.FromCurrent>>.View.Select(this);

how can I fix this error? As I’m new to acumatica , I don’t know what I have done wrong in my code. So If someone could help me in this and needs the full code let me know please.

Thank you in advance.