There are a few issues with the 7.x-1.0 release of Views Calc. These have apparently been fixed/committed, but the latest dev release doesn't include these fixes.
This is due to the fact that the 7.x-1.x-dev release is based on the 'master' branch which is no longer being updated.
The 7.x-1.x branch is the one with the latest changes/fixes, however the only way to use this on a site is via Git...
Could you please create a new 7.x-1.x-dev release based on the 7.x-1.x branch and remove the old, master-based 7.x-1.x-dev release to avoid confusion?