Word 97 VBA

I am enhancing an ancient WIN32 application using DDE to communicate w/ WORD97. I am having problems importing a large string into WORD from my C application. I receive a message stating Buffer too small for import string, and WORD freezes. I've tried breaking up the string and performing multiple DDE_REQUEST statements (each to bring in 250 characters), but it still freezes on the third try (ie. after 500 characters have successfully been imported). Any suggestions? Upgrading to WORD2000 or using COM is not a viable option.