grunt-sass not compiling, but successful compile at sassmeister

[aaronharding]

This is my first time using sass and I'm having trouble compiling. This is my sass:

$gridcolumns: 6;
$gutter: 16;
$width: 964;

.section {
  overflow: hidden;
}

.section .row {
  width: 100%;
  max-width: $width + px;
  margin: 0 auto;
  overflow: hidden;
  padding: 0 (($gutter/$width*100)/2);
}

.cell {
  float: left;
  padding: 0 (($gutter/$width*100)/2);
}

@for $i from 1 through $gridcolumns {
    .width-#{$i} {
        width: percentage( $i * (1/$gridcolumns) );
    }
}

@for $i from 1 to $gridcolumns {
    .cell.push-#{$i} {
        margin-left: percentage( $i * (1/$gridcolumns) );
    }
}

@for $i from 1 to $gridcolumns {
  .cell.pull-#{$i} {
        margin-right: percentage( $i * (1/$gridcolumns) );
    }
}

And this is the error I get:

Running "sass:structure" (sass) task
Verifying property sass.structure exists in config...OK
Files: structure.sass -> structure_sass.css
Options: precision=5, errLogToConsole
>> invalid property name
>>   Line 5  Column 10  structure.sass
Warning:  Used --force, continuing.
Warning: invalid property name Used --force, continuing.

What's odd though, is that even when I change the sass to:

$gridcolumns: 6;
$gutter: 16;
$width: 964;

.section {
  overflow: hidden;
}

or even

.section {
  overflow: hidden;
}

I still get the same error (this error is from running the 2nd from above):

Verifying property sass.structure exists in config...OK
Files: structure.sass -> structure_sass.css
Options: precision=5, errLogToConsole
>> invalid property name
>>   Line 1  Column 10  structure.sass
Warning:  Used --force, continuing.
Warning: invalid property name Used --force, continuing.

Although, I can successfully compile with http://sassmeister.com/. So what do? I'm already running with errLogToConsole and the verbose flag. What's wrong with the {?

[kevva]

Issues with the output should be reported on the libsass issue tracker.

[aaronharding]

Did not see that, sahrry. And thanks!