Dear Mariam,

Its tricky to use EtBr and Calcenin at the same time as both will give a florescence of almost the same colour. This makes it difficult to visualize unless you have a real good florescent microscope. I would suggest you use DAPI for nuclear or DNA staining as it will be having blue emission which you can differentiate from Calcenin staining. 

make a stock solution of 5 mg/mL DAPI stock solution (14.3 mM for the dihydrochloride or 10.9 mM for the dilactate), dissolve the contents of one vial (10 mg) in 2 mL of deionized water (dH2O) or dimethylformamide (DMF). The less water-soluble DAPI dihydrochloride may take some time to completely dissolve in water and sonication may be necessary.

Dilute the DAPI stock solution to 300 nM in PBS. Add approximately 300 µL of this dilute DAPI staining solution to the coverslip preparation, making certain that the cells are completely covered.

Hope it helps.

I think you mean Calcein, not calcenin (never heard of a chemical called this), in which case this staining will be fine. EtBr will only stain dead or permeabilized cells. A total DNA counterstain like Hoechst 33342 will be helpful for getting total nuclei counts. Spectrally, these will all work together just fine.

Hoechst: 1-10 µg/mL

Calcein AM: 1-5 µM

EtBr: 1-5 µM

EtBr binding it is reversible. Therefore it is better to adquire images right after the staining.