LTspice no finding parameter definition
In LTspice, expressions are wrapped with braces: {}. Almost always, anyway. (I'm never 100% sure in any given situation. There seem to be various places where the parsing is a little bit different for one reason or another.)
In the case of resistors, you are allowed to use R=&lt;expr&gt; without using R={&lt;expr&gt;}. No, I don't know why. But I have noticed that with other sources you can sometimes use V=&lt;expr&gt; or I=&lt;expr&gt;, too. So if you are fond of these kinds of writing styles, you'll have to experiment. Usually, though, the braces are the way to go as your first attempt. Usually, it works.
There are lots of other details you'll need to learn to help parameterize schematics. (If I had time tonight, I might list a few of them. But for now, I guess the above will do.) Just be on the watch for them. Use the included help, also. It's not perfect and there is much one could wish was added to it. But it's a start and often enough I can figure things out by reading through it. In the few cases where I cannot, I then resort to web searches and/or experimentation.
The netlist is also of some help. Sometimes you can see something there that just looks &quot;impossible to parse right.&quot; If you see something like that, you are probably right and this is why it's not working. (Spaces in named nodes, for example, would make it impossible to parse because spaces are used to separate keywords on the Spice line and so it would certainly confuse things. That's just an example to help make the broader point.)