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# Invalid units in input position

Issue:

Why am I getting the error, Invalid units in input position 1?

![The invalid units error message](https://files.learn.ntop.com/help-articles/implicit-modeling/360099995053.png)

## Applies to:

* Blocks that input different units depending on how it is used, such as the Ramp block.

## Cause:

These blocks allow for various units in their inputs. By default, they don't have a set unit value. Without a defined unit an error will occur.

## Solution:

Write in the units you need when there are no units shown in the far right of the input. Watch the gif below to see how it works with the Ramp block.

![The gif shows how adding units to a unitless input clears up the error message.](https://files.learn.ntop.com/help-articles/implicit-modeling/360099996273.png)

## Keywords:

*error ramp block empty input invalid units in position*