Formatting text to formula

I am trying to make a formula which calls an external file reference by tying together the contents of cells in my workbook. An example may illustrate most clearly :-

Cell A1 contains the number 650
Cell B1 contains the text
'T:\location\[CCF

Cell C1 contains the text
.xls]Summary'!$b$1

Cell D1 contains the formula
=("="&B1&A1&C1)

I want to look up a particular cell B1 in file CCF 0650.

I have tried using INDIRECT but this just returns a #REF error. Any ideas?