[Axl] axl_doc_parse_from_file aborts program in subfunction

[Raphael Schneider]

I've got a problem with parsing a file. I've got a subfunction that 
starts as stated:

int write_frq(int n_pump, double frqs[]) {
     axlError *a_err = NULL;

     axlDoc *doc = NULL; //axl library document object
     axlNode *root = NULL; //axl library root node object
     axlNode *node = NULL; //node object for navigation

     printf("DEBUG - write frq() axl variables defined\n");

     //get doc reference
     doc = axl_doc_parse_from_file("GAtest1_input.xml", a_err);
     printf("DEBUG - write_frq() error: %d %s\n", 
axl_error_get_code(a_err), axl_error_get(a_err));
     if (doc == NULL) {
         printf("DEBUG - writefrq() - file not found!\n");
         axl_error_free(a_err);
         exit(EXIT_FAILURE);
     }

     printf("DEBUG - write_frq() doc loaded to axl\n");

[...]

The problem is, that the program just aborts when trying to load the doc 
from axl_doc_parse_from_file. I don't get any error codes anymore, nothing.
The exact same code however works fine if I run it in its own int main().
Anyone an idea what's wrong here?

Thanks
Raphael