Date field not displaying calendar button image

Hi,
On our very old v1.1.0 event booking component on Joomla 1.5 we used the date field with the calendar popup for date of birth and other fields where users needed to select a date. However on the v2.0.3 on Joomla 3.4.3 the calendar image does not appear next to the date field. I compared the code between the 2, and if I change the button class from btn to calendar then it displays.

Also, can you see that strange piece of code ..="" in the date field input line in the v2.0.3 code? I can't see this in any other fields, maybe this is a typo causing the error? I was thinking it was my template's css, but now I can see the different class I'm thinking it's just a little bug?

EDIT: I have attached the code in the txt attachment, I kept getting a 403 Permission error when trying to post the code, even when it's in the code tags.

I can send URL's if needed

Thanks,
Aaron