double integral matlab error

A small question :

This is my script ;

R=4

SL=2

CR = @(s,t)(1/pi).*exp(-0.5*(s.^2+t.^2))

smax=@(t)-R.*(t-SL)

smin=@(t)-R.*(t+SL)

tmax=inf

tmin=SL

qCR = integral2(CR,smin,smax,tmin,tmax)

PR = @(s,t)(1/pi).*exp(-0.5*(s.^2+t.^2))

smax=inf

smin=@(t)R.*(SL-t)

tmax=SL

tmin=-SL

qPR = integral2(PR,smin,smax,tmin,tmax)

but Matlab show me this error : Error using integral2 XMIN must be a floating point scalar. Error in qCR = integral2(CR,smin,smax,tmin,tmax)

Thank you :)