# 0014: Incorrect expression

There is an expression used without an opcode, and the operand types are incompatible.

The operands are incompatible when:

* one operand is a variable which type has been [declared](https://docs.sannybuilder.com/language/data-types/variables#declaring-a-variable-type) using the `var` keyword, but the type of another operand is different:

```pascal
var 0@: Int

0@ = 1.0
```

* both operands are variables that were not declared via `VAR..END`
* one of the operands is impossible. For example, a number on the left side of an assignment statement:

```pascal
5=6
```

**Possible solutions:** check the correctness of this expression. Either:

* re-declare the variable with the correct type
* declare both variables using the `var` keyword
* fix the expression using correct values\\