Removing 2003 headlight rubber cover

I'm trying to change a headlight in my 2003 Tacoma 2wd. I have the connector unplugged but can't pull off the rubber cover. The rubber cover has a tab that says "pull" which I've done - pulled straight back and also up first and then straight back but it hasn't budged. My guess is that I just need to pull harder straight back but I thought I'd ask in the forum first for advice. Thanks.

 

Yes, just pull straight back

 

Yeah pull harder. It might be stuck from years of heat and dust but it fibres right off

 

Thanks for your help CR250jumper and Mr Biscuits!

 

ya they're hard as hell to get off. i replaced the bulbs on my 04 and they were a bitch to get off but easy to get back on