getDate from String ? Should be easy

This should be so simple, yet I'm having issues.

I'm passing a date to a page parameter and then want to pick the value up for some labelling. The URL is passing :

...#Page:Dev_Home_Generic?startDate=01-Jan-2022&endDate=31-Dec-2022

and I'm trying to get the Month and Year but when I try to convert the parameter to a date it either gives me a weird response or an error

varThisYearText= toDate(input.startDate,"dd-MMM-YYYY");
...
<text type='Text' value='<%=varThisYearText%>' size='15px' color='#000000' marginBottom='5px'> </text>

gives the result 26-Dec-2021

When I look up the deluge help page for getDate : https://www.zoho.com/deluge/help/functions/datetime/get-date.html it says :

Note: This function is applicable to all services, except Zoho Creator.

So how do I convert a string of "01-Jan-2022" to "Jan22" ?