Markers don't show up just as soon as I switch from Multi pass to Singe pass rendering mode

They're are really important in my game , if it's impossible to have it in single pass then is there any alternative ways?

you can have markers in SINGLE_PASS
if you enable D.hwDepthBuffer(true) and you have video card GeForce>=8 || Radeon>=1k

if not, then you can try using normal meshes which have material.tech=MTECH_BLEND;