horizontal line group on RTF

 Hi. Well, I have this problem where I need to add all the invoice numbers from a document, and i have to print them in one line the xml is like this:

<OutboundDocument>

    information

    <DocumentPayable>

        <InvoiceNumber>25</InvoiceNumber>

    </DocumentPayable>

    <DocumentPayable>

        <InvoiceNumber>52</InvoiceNumber>

    </DocumentPayable>

    <DocumentPayable>

        <InvoiceNumber>120</InvoiceNumber>

    </DocumentPayable>

</OutboundDocument>

i created a repeating group, however it prints them like this:

25

52

120

and what i need is:

25  52  120

i have tried with <for-each@inlines:DocumentPayable> and it displays only the first value, 25

trying to use <?if@inlines:DocumentNumber/ReferenceNumber!=0?> inside a regular for-each also only displays the first result

any help?