Why is this not a valid XML DTD? (Parameter entity and #PCDATA)

Question

Hi,

Using the DTD validator here, I am informed that the following DTD is invalid.

<!ENTITY % text "(#PCDATA|L)*">
<!ELEMENT H         (%text;)+>
<!ELEMENT L         (#PCDATA)>

The error message is: "A '(' character or an element type is required within declaration of element type "H"." at line 2, column 22.

Can anyone please point out why it is invalid? And how can I make it valid? The error message is not exactly very friendly to me. Thanks.