Think of some examples. Here's a classic Thomist "analogical" term: "healthy". Properly speaking it is only bodies that are healthy, and for a body to be healthy is for it to be in good working order. For medicine to be healthy isn't for the medicine to be in good working order, it is for the medicine to have the power to put bodies into good working order. So here we clearly have two distinct but senses of "healthy".
So let's consider an example of a syllogism.
(1) If something is healthy, it is good.
(2) This medicine is healthy.
(3) Therefore, this medicine is good.
Understand the occurrence of "healthy" in the first line as meaning healthy in the sense that bodies are healthy. Do we have a valid syllogism here? According to Thomists yes; according to Scotists and those who are suspicious of analogy no.