how to build DDE link with text from another cell
 

Using a DDE link in Excel is pretty simple. In my case, I use links like
=gol|cot!IBOV.ult
to recover data from a provider named GOL.
How can I obtain the same result when I need to build the link based on the
text content of a given cell? For example, assume cell A1 contains the text
IBOV. I know I can build the string
gol|cot!IBOV.ult
by using the formula
"gol|cot!"&A1&".ult"
But, when I try to use the INDIRECT function with this formula as argument,
it doesn't work! The result is a #REF.
How can I do it?
Thanks in advance.