textbox in a user form

I am just creating a user form (my very first user form). it just a text box and a command button to save the data entered in the text box to a cell
in a particulary sheet.

The issue is whenever i want to enter a text in the box in the run mode, it going back to designer mode .

unable to understand the issue. i have checked the properties of the text box
Enabled= true / i have tried false also
locked= false
visible= true

What can be the problem. suggestions please

invoking userform through F5.

It doesnt have any code except the text box where the value is entered, submit button is clicked it saves the value on the sheet
and exit button unload the user form . beyond this there is nothing.

The issue is the focus is not going into text box either using tab, or by mouse clicking into the empty text box.

Yes it is . and it just started working now. i also found enable in false mode while it should be true.

i have created other text boxes along with the old one I think the problem lies in the property settings for the text box
which seem to be ok now.

There is no code except unload me in exit button. and text value assigned to a cell on the sheet on the submit button.

Anyways thanx a lot mikerickson for your help.