Expression not updating when dataset changes

I have this expression binding on a text box

try(tostr(toint(lookup({Root Container.SalesData},{Root Container.Container_1.SKU},0,"SKU","Outlet_Previous"))),"")

on the dataset {Root Container.SalesData} i have a dynamic SQL query bound that uses drop down box labels for parameters. when I change the drop down selections i can see the dataset changes, but my lookup binding on my text box does not seem to update every time. the data set always has the same column names, amount of rows, and amount of columns the only thing that changes in the data set is the values in the cells. any ideas why my expression is not updating when the dataset changes?

Thank you,

What is the {Root Container.Container_1.SKU} property bound to?

a lookup on the same dataset

lookup({Root Container.SalesData},toint(split({Root},"_")[1,0]),"","RowNum","SKU")

could the lookups be firing out of order. let me try combining them into one expression.

combining the lookups does not seem to solve the issue.

this is what i did that seems to force the expressions to update.

on the drop down box I put this code

if(event.propertyName == "selectedIndex"): event.source.parent.parent.SalesData = system.dataset.toDataSet(["Distributor","Custnmbr","SKU","Sales_Previous"\ ,"Sales_Current","Outlet_Previous","Outlet_Current","SortOrder","Label","RowNum"],[])

now when one of the parameters is changed the dataset is set with 0 rows before the drop down label changes. let me know if you see any issue with this.