re: smartlyte electrolyte analyzer

 I have smartlyte analyzer that is running for period of two months but now it gives me on the screen"inspect reference housing. I followed all the possibilities for maintenance in the "operators manual” such as- check for proper filling of the reference housing- ensure that the reference tubing is securely connected to the receptacle- since this test utilize standard A. make sure that it is aspirated properly into the measuring chamber. if not replace the ise pack- clean the reference housing-   please I want a solution to my problem.  thank you very much