Error when importing file (File to import not found or unreadable:)

Hi,
using Compass 1.0.3 (Polaris) on a mac (OSX 10.10.3)
I have 2 files my application.css.scss and _variables.css.scss.

Gulp compass command works ok, until I try and import _variables.css.scss.
When I run gulp compass when trying to import this file _variables.css.scss I get.

`
error sass/application.css.scss (Line 1: File to import not found or unreadable: variables.`

Have had a good look online and have not found any solid solutions for this error.
Has anyone encountered this before or possibly found a fix for this?

here is the gulp task I am running btw:
```
gulp.task('compass', function() {
gulp.src('./source/assets/stylesheets/*.scss')
.pipe(compass({
project: path.join(__dirname, './source/assets/stylesheets'),
sass: 'sass',
css: __dirname + '/build/source/assets/stylesheets',
debug: true,
sourcemap: true
}))
.pipe(gulp.dest('app/build/assets'));
});

```
If anyone could help out it would be greatly appreciated.

Start by reproducing the gulp compass task from the issue with source/assets/stylesheets/application.css.scss and _variables.css.scss, then inspect how the configured project and sass paths resolve the variables import. Done means gulp compass can import _variables.css.scss without the “File to import not found or unreadable” error.

Written by the indexing model from the issue text.