Works on one wiki, not the 2nd

[jukwaphil1]

I've installed all 3 plugins (including Google Authenticator). Worked fine on my local wiki and when I installed on it my NAS (which I keep the same as my local using a sync plugin), I get the following.

You have enabled two factor authentication, but no providers are properly configured. Please complete the configuration of at least one provider or disable two factor authentication.
Fatal error: Uncaught Error: Call to undefined function ImageCreate() in /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/phpqrcode.php:985 Stack trace: #0 /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/phpqrcode.php(943): QRimage::image(Array, 3, 4) #1 /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/phpqrcode.php(3302): QRimage::png(Array, Resource id #163, 3, 4, false) #2 /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/phpqrcode.php(3094): QRencode->encodePNG('otpauth://totp/...', Resource id #163, false) #3 /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/helper.php(132): QRcode::png('otpauth://totp/...', Resource id #163) #4 /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/helper.php(38): helper_plugin_twofactorgoogleauth->generateQRCodeData('[redacted]', '[redacted]') #5 /volume1/web/dokuwiki/lib/plugins/twofactor/action.php(179): helper_plugin_twofactorgoogleauth->renderProfileForm() #6 /volume1/web/dokuwiki/lib/plugins/twofactor/action.php(350): action_plugin_twofactor in /volume1/web/dokuwiki/lib/plugins/twofactorgoogleauth/phpqrcode.php on line 985

I have tried removing and reinstalling the 3 plugins but no joy. Thanks.