Button text not showing

Hi there,
I have a little problem. I’m using Shopisle and Woocommerce and I integrated the Newsletter-form into the footer.
The problem: My send/submit-button is not showing.
I already looked into css and changed the background colour, but there’s still no text.
My website: https://https://web28.c20.webspace-verkauf.de
Like I said, the problem is at the bottom of site.

My css:
.widget form input[type=”submit”] {
background: #424242 none repeat scroll 0 0;
border: medium none;
color: #ffffff !important;
font-size: 14px;
height: 33px;
line-height: 38px;
outline: medium none;
overflow: hidden;
position: relative;
right: 1px;
text-indent: -1e+8px;
top: 0;
width: 100px;
}

Thank you so much!
Miriam