hi,
I used mamory maped lcd and works fine!

that does not mean that it will work same for another configuration. Which LCD do you use? What is the OSC frequence of your MCU? Which 8051 model do you use? There are a lot of questions as well.
Now why.

there are two possible problems:
1) T_as - Address set-up time (RS, R/W to E).
This parameter says about that RS and R/W must be set at no less than 60ns before Strobe. If you make E signal just from address lines decoder then it comes to LCD before /WR or /RD, that`s wrong. It you involve /WR and /RD for decoding as well as address lines then E comes nearly at same time as /WR, that`s wrong too.
2) PW_EH - The Enable pulse width (high level) must be no less than 450ns. Well, assume we made E signal using /WR or /RD as source. For standard 8051 part the time of /WR and /RD signal is calculated as:
6*t_CLCL-100(ns). So only if OSC frequency below 11MHz then we may produce enough length of E signal. Otherwise it will be too short for correct strobe.

Finally, my project uses direct LCD addressing via MOVX. But it has Altera CPLD between MCU and LCD so I create all timings with CPLD.

Regards,
Oleg