We, too, use the DAKO mAb (M7155) for cyclin D1 detection.  Unlike most of our IP stains that are now performed with EnVision+, we continue to use DAKO's LSAB+ for cyclin D1 (one of my hematopathology colleagues likes the immunoreactivity with LSAB+ better than that with EnVision+).  Personally, I think the secret (as usually) is having well fixed and processed tissue, as well as prolonged heat treatment.  We pretreat our tissue sections with DAKO's "High pH" retrieval solution in a 98 degree waterbath for forty (40) minutes.  In addition, we incubate with the mAb diluted 1:1,000 overnight at RT.  You can also incubate 30 minutes but you will have to decrease the dilution to approximately 1:200.  If you continue to have problems please contact me and I can send you some of our positive control sections.

R. Cartun