Form buttons (Submit, add, remove) not displayed in Engine

Dear all,
I have created my application which is working perfectly in the studio, but when I input into Engine I cannot get the buttons displayed in the forms…
The link widget are working fine, but as soon as I choose button (I need button to add/remove items) to a collection, the button is not displayed on the online form… Instead there is just a small grey square which does not produce any action when I click on it.
Please help! Thanks in advance.
Tim

Engine Log:
2019-04-26 03:33:55.655 +0000 INFO: org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/bonita] RestletServlet: [Restlet] ServerServlet: component class is null
2019-04-26 03:33:56.217 +0000 INFO: org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/bonita] RestletServlet: [Restlet] Attaching application: org.bonitasoft.web.rest.server.BonitaR$
2019-04-26 03:33:56.243 +0000 INFO: org.restlet.Component.BonitaRestletApplication Starting org.bonitasoft.web.rest.server.BonitaRestletApplication application
2019-04-26 03:34:11.219 +0000 INFO: java.sql.DatabaseMetaData HHH000262: Table not found: ORDERITEM
2019-04-26 03:34:11.222 +0000 INFO: java.sql.DatabaseMetaData HHH000262: Table not found: ORDERITEM
2019-04-26 03:34:11.224 +0000 INFO: java.sql.DatabaseMetaData HHH000262: Table not found: ORDERITEM
2019-04-26 03:35:33.862 +0000 INFO: org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/bonita] CustomPageRestletServlet: [Restlet] ServerServlet: component class is null
2019-04-26 03:35:37.504 +0000 WARN: org.hibernate.ejb.HibernatePersistence HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; $
2019-04-26 03:35:37.510 +0000 WARN: org.hibernate.ejb.HibernatePersistence HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; $
2019-04-26 03:35:37.514 +0000 WARN: org.hibernate.ejb.HibernatePersistence HHH015016: Encountered a deprecated javax.persistence.spi.PersistenceProvider [org.hibernate.ejb.HibernatePersistence]; $
2019-04-26 03:41:08.476 +0000 INFO: org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/bonita] CustomPageRestletServlet: [Restlet] Attaching application: org.bonitasoft.web.rest.serv$
2019-04-26 03:41:08.477 +0000 INFO: org.restlet.Component.BonitaRestletApplication Starting org.bonitasoft.web.rest.server.BonitaRestletApplication application

Hello @t.delhaise_1381938

This log can not help.

I think your problem about css or some exception occurred in your page.
I suggest try to inspect your page in browser and go to console tab and check all warning or error relative to the button or the page.

Please report the result.

Thanks ,
Ali

Hello the.shirini
I solved the issue by re-designing the pages from studio. So I guess that that was a small issue in the page.
Thank you.