Import of icas file to Thunderbird/ Calendar fails, no error message or anything; any ideas? (Win 8.1)

Question

File originally exported from Microsoft Works Calendar. Is an ics format file which Thunderbird Calendar uses. There is an 'Events and Tasks/ Import' option in the toolbar but using this and selecting the ics file produces no discernable result; not even an error message.
Should import be possible? If so, are there limits on size, dates? Any ideas gratefully received.

Answer 1

<ol>
<li>In Thunderbird, select the Calendar tab.</li>
<li>Right click on a calendar and select 'New Calendar...'.</li>
<li>Click 'On My Computer' and 'Next'.</li>
<li>Give your calendar a name (e.g. Home), choose a color for it, and click 'Next'.</li>
<li>Click 'Finish'.</li>
<li>From the 'Events &amp; Tasks' menu, select 'Import...'.</li>
<li>Highlight the .ics file and click 'Open'.</li>
<li>On the small 'Select Calendar' screen, highlight 'Home' and click 'OK'.</li>
<li>There will be a delay of several seconds while Lightning processes the calendar file.</li>
<li>Note that a calendar is displayed if it is checked, and hidden if not checked.</li>
</ol>
Does that work? How large is your .ics file? Do you have lots of old entries?