Sandra,
I am suggesting to use a little bit of gelatin in your water bath to solve the problem. If it didn't work, try to coat slides with gelatin solution
Recipe for Chrome Alum Gelatin Solution:
Gelatin, type A, 275 Bloom -------------------- 3 g
Chromium potassium sulfate ------------------ 0.5 g
Distilled water ----------------------------------- 1000 ml
Heat to 60 C to dissolve gelatin and then add chromium potassium sulfate.
Hope this helps.
Richard