Crappy sensorgrams

Hi SPR gurus,
I am new to SPR but I have been trying this for 2-3 months now. I have liposomes as ligand and protein as analyte and using Nicoya Liposome sensors in Nicoya Open SPR machine. I am using fresh buffers, degassed, analyte freshly diluted in running buffer and protein aliquoted and checked. Also check the liposomes using nanosight. I have always been getting really crappy sensorgrams-there is always some bulk shift, dissociation is very long (so shifted to single cycle kinetics) and variation from one run to another. I am at my wit's end. Can anyone help me out? I am not sure what am I doing wrong. This is an one-channel instrument so I subtract the buffer/control ligand data from my reading.

Thanks, 
Sonya

Anyone?

If the no response is due to inadequate information, here are what I can think of-
+ the instrument used-Nicoya OPEN SPR(one channel)
+ immobilization conditions (concentrations/contact time of activation, ligand and deactivation)
-50mg/ml 100nm Liposome vesicles, contact time 300s, flow rate 20uL/min
+ the buffers and regeneration condition used-HEPES-NaCl pH 7.4, regeneration 50mM NaOH
+ ligand and analyte (name, Mw, concentration and buffer composition) Analyte: purified protein 15 KDa

Hi Sonya,Your curves look a bit bumpy, but this should not affect the result too much. The bulk shift you observe in the fitting is a mathematical thing. Look at www.sprpages.nl/data-fitting/datafit-tro...ing/high-buffer-jump for some explanation.
It looks like that you are well under way. What is hard to see from the figures is the analyte concentrations you injected and the corresponding curves. Can you clarify this (colour = nM analyte). For a better fitting I would make the dissociation a little longer (e.g., 300 second) if possible.
Kind regards
Arnoud