[TYPO3] MailformPlus: checkbox and conditions in TS?

[Gerhard Mehsel]

Hello,

how can I make an MailformPlus errorCheck for a checkbox?
This is my template:

<input type="checkbox" name="check[]" id="check_0" value="yes" 
###checked_check_yes###/>

I want to check the state of that checkbox in MailformPlus TS because I 
have to require additional fields then.

I tried this:
[globalVar = GP:check|0 = yes]
plugin.tx_thmailformplus_pi1.default.email_requiredfields = additional1, 
additional2 
plugin.tx_thmailformplus_pi1.default.email_requiredfields.country = 
required, notDefaultValue
[global]

In debug state I can see that the array for this checkbox is filled:
.... [check] => Array ( [0] => yes ) .....

Can anyone help?

Thanks alot
Gerd