Hi @Hawkman ,
Maybe you could also check with the below Expression :
DataTable.Select("[LookUpColumnName]='"+ AnotherStringVar.Trim + "'")(0).Item(4).ToString
or
DataTable.AsEnumerable.Where(Function(x)x("LookUpColumnName").ToString.Equals(AnotherStringVar.Trim)).First.Item(4).ToString
Let us know if you are still facing issues with both the Expressions and maybe let us know what were the error messages for each one.