You set the label as recordType? You mean you set the field name to "recordType"? Hidden fields don't use the label box.
Here's the deal, Salesforce uses its internal ID there... so you can’t enter "MyLeadRecordTypeName"... it's more like "012d0000000lD0U" -- note that is just what my install used you'll need to find the identifier your system uses for each record type and use that as the value.
To do that, you can use Salesforce's web to lead form generation tool, then grab the ids from the code (clunky, but the only way I know of to get at these).
Step 1 tells you where to go. Skip steps 2 &3 and go to 4.
Make sure you add LeadRecordType to the Selected Fields (you can remove the other fields), then click generate.
You'll get a bunch of HTML on the next screen -- you're looking for this bit:
<label for="recordType">Lead Record Type</label>
<select id="recordType" name="recordType">
In this case:
012d0000000lD0U = TestLeadRT
012d0000000lD0Z = TestLeadRT2