(This is a head slap)
you forgot the closing '}' on each one, so
HTML Code:
ody.page-id-5 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important;
body.page-id-7 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important;
body.page-id-10 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important;
body.page-id-26 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important;
body.page-id-28 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important;
should be
HTML Code:
ody.page-id-5 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important; }
body.page-id-7 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important; }
body.page-id-10 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important; }
body.page-id-26 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important; }
body.page-id-28 div#imagecontainer {
background-image: url(http://susan.bangonwebdesign.ie/wp-content/themes/atahualpa/images/header/HeaderLogo1.jpg) !important; }