[TYPO3] problem with using checkbox values in srfeuserregister

[Jeroen Visser]

Hi All,
I have extended the srfeuserregister form with a own extension for adding more field to the form.
The user must use check boxes to say what kind of magazine he would like to receive. This can be more than one.

In the kickstarter I have chosen the field type: "Checkbox, 4  boxes in a row" with 2 checkboxes present. Then I have labeld these 2 checkboxes.

The ext_tables.php looks like this then:
$tempColumns = Array (
	"myNewFieldName" => Array (		
		"exclude" => 1,		
		"label" => "LLL:EXT:roq_sr_feuser_register/locallang_db.xml:fe_users.myNewFieldName",		
		"config" => Array (
			"type" => "check",
			"cols" => 4,
			"items" => Array (
				Array("LLL:EXT:roq_sr_feuser_register/locallang_db.xml:fe_users.myNewFieldName.I.0", ""),
				Array("LLL:EXT:roq_sr_feuser_register/locallang_db.xml:fe_users.myNewFieldName.I.1", ""),
			),
		)
	),
...
...
);

The new fields are added to the TS.
When I check both checkboxes the values are posted in an array as expected. The confirmation page shows always the first one checked.
It seems that the name of the input field is false. This is for both fields:

name="FE[fe_users][myNewFieldName][]

Should it not be:
name="FE[fe_users][myNewFieldName][0]
name="FE[fe_users][myNewFieldName][1]

Hope someone can help me out here.

Kind regards,
Jeroen