You have some fundamental misunderstandings about how Mathcad works.
Assignments:
The normal assignment is :=. It assigns a value (or values) to a variable at the worksheet level
The local assignment within a program is the left shaft (roughly <--).
The global assignment is the the triple bar.
Subscripts:
You get an array subscript using "['. this indexes into an array. If the subscript is a variable name, then the variable must be defined as a numeric value.
You get a literal subscript using <Ctrl> -. This is just part of the variable name. It is only cosmetic, and cannot subsequently be used for anything.
Your assignments are a seeming random mix of the above. On the LHS you have both literal and array subscripts, your assignments are either local program assignments or the normal worksheet assignment, and in many cases the || either side of the RHS indicates you have a one line program (functionally, this makes no difference, but it looks strange). In the cases where you have an array subscript on the LHS (e.g. ix[FW50) the subscript is undefined. The only reason you don't get an error is because you also use the local program assignment, but don't have any assignment at the worksheet level (i.e. no :=), so Mathcad just ignores the entire statement.
I've attached a worksheet that will hopefully get you started. It assigns the properties to a matrix, and then shows you how to index into that matrix.
